The enthalpy of solution for NaOH is -44.46 kJ/mol. What

Calculate the percent by mass of the solute in each of the following aqueous solutions: (a) 5.50 g of NaBr in 78.2 g of solution, (b) 31.0 g of KCl in 152 g of water, (c) 4.5 g of toluene in 29 g of benzene

Calculate the amount of water (in grams) that must be added to (a) 5.00 g of urea (NH2)2CO in the preparation of a 16.2 percent by mass solution, and (b) 26.2 g of MgCl2 in the preparation of a 1.5 percent by mass solution.

Calculate the molality of each of the following solutions: (a) 14.3 g of sucrose (C12H22O11) in 676 g of water, (b) 7.20 moles of ethylene glycol (C2H6O2) in 3546 g of water

Calculate the molality of each of the following aqueous solutions: (a) 2.50 M NaCl solution (density of solution 5 1.08 g/mL), (b) 48.2 percent by mass KBr solution.

Calculate the molalities of the following aqueous solutions: (a) 1.22 M sugar (C12H22O11) solution (density of solution 5 1.12 g/mL), (b) 0.87 M NaOH solution (density of solution 5 1.04 g/mL), (c) 5.24 M NaHCO3 solution (density of solution 5 1.19 g/mL).

For dilute aqueous solutions in which the density of the solution is roughly equal to that of the pure solvent, the molarity of the solution is equal to its molality. Show that this statement is correct for a 0.010 M aqueous urea (NH2)2CO solution.

The alcohol content of hard liquor is normally given in terms of the proof, which is defined as twice the percentage by volume of ethanol (C2H5OH) present. Calculate the number of grams of alcohol present in 1.00 L of 75-proof gin. The density of ethanol is 0.798 g/mL

The concentrated sulfuric acid we use in the laboratory is 98.0 percent H2SO4 by mass. Calculate the molality and molarity of the acid solution. The density of the solution is 1.83 g/mL.

Calculate the molarity and the molality of an NH3 solution made up of 30.0 g of NH3 in 70.0 g of water. The density of the solution is 0.982 g/mL.

The density of an aqueous solution containing 10.0 percent of ethanol (C2H5OH) by mass is 0.984 g/mL. (a) Calculate the molality of this solution. (b) Calculate its molarity. (c) What volume of the solution would contain 0.125 mole of ethanol?

How do the solubilities of most ionic compounds in water change with temperature? With pressure?

Describe the fractional crystallization process and its application.

A 3.20-g sample of a salt dissolves in 9.10 g of water to give a saturated solution at 25C. What is the solubility (in g salt/100 g of H2O) of the salt?

The solubility of KNO3 is 155 g per 100 g of water at 75C and 38.0 g at 25C. What mass (in grams) of KNO3 will crystallize out of solution if exactly 100 g of its saturated solution at 75C is cooled to 25C?

A 50-g sample of impure KClO3 (solubility 5 7.1 g per 100 g H2O at 20C) is contaminated with 10 percent of KCl (solubility 5 25.5 g per 100 g of H2O at 20C). Calculate the minimum quantity of 20C water needed to dissolve all the KCl from the sample. How much KClO3 will be left after this treatment? (Assume that the solubilities are unaffected by the presence of the other compound.)

Discuss the factors that influence the solubility of a gas in a liquid.

What is thermal pollution? Why is it harmful to aquatic life?

What is Henrys law? Define each term in the equation, and give its units. How would you account for the law in terms of the kinetic molecular theory of gases? Give two exceptions to Henrys law.

A student is observing two beakers of water. One beaker is heated to 30C, and the other is heated to 100C. In each case, bubbles form in the water. Are these bubbles of the same origin? Explain.

A man bought a goldfish in a pet shop. Upon returning home, he put the goldfish in a bowl of recently boiled water that had been cooled quickly. A few minutes later the fish was found dead. Explain what happened to the fish.

A beaker of water is initially saturated with dissolved air. Explain what happens when He gas at 1 atm is bubbled through the solution for a long time.

A miner working 260 m below sea level opened a carbonated soft drink during a lunch break. To his surprise, the soft drink tasted rather flat. Shortly afterward, the miner took an elevator to the surface. During the trip up, he could not stop belching. Why?

The solubility of CO2 in water at 25C and 1 atm is 0.034 mol/L. What is its solubility under atmospheric conditions? (The partial pressure of CO2 in air is 0.0003 atm.) Assume that CO2 obeys Henrys law.

The solubility of N2 in blood at 37C and at a partial pressure of 0.80 atm is 5.6 3 1024 mol/L. A deepsea diver breathes compressed air with the partial pressure of N2 equal to 4.0 atm. Assume that the total volume of blood in the body is 5.0 L. Calculate the amount of N2 gas released (in liters at 37C and 1 atm) when the diver returns to the surface of the water, where the partial pressure of N2 is 0.80 atm.

What are colligative properties? What is the meaning of the word colligative in this context?

Write the equation representing Raoults law, and express it in words.

Use a solution of benzene in toluene to explain what is meant by an ideal solution

Write the equations relating boiling-point elevation and freezing-point depression to the concentration of the solution. Define all the terms, and give their units

How is vapor-pressure lowering related to a rise in the boiling point of a solution?

Use a phase diagram to show the difference in freezing points and boiling points between an aqueous urea solution and pure water

What is osmosis? What is a semipermeable membrane?

Write the equation relating osmotic pressure to the concentration of a solution. Define all the terms and specify their units

Explain why molality is used for boiling-point elevation and freezing-point depression calculations and molarity is used in osmotic pressure calculations.

Describe how you would use freezing-point depression and osmotic pressure measurements to determine the molar mass of a compound. Why are boiling-point elevation and vapor-pressure lowering normally not used for this purpose?

A solution is prepared by dissolving 396 g of sucrose (C12H22O11) in 624 g of water. What is the vapor pressure of this solution at 30C? (The vapor pressure of water is 31.8 mmHg at 30C.)

How many grams of sucrose (C12H22O11) must be added to 552 g of water to give a solution with a vapor pressure 2.0 mmHg less than that of pure water at 20C? (The vapor pressure of water at 20C is 17.5 mmHg.)

The vapor pressure of benzene is 100.0 mmHg at 26.1C. Calculate the vapor pressure of a solution containing 24.6 g of camphor (C10H16O) dissolved in 98.5 g of benzene. (Camphor is a low-volatility solid.)

The vapor pressures of ethanol (C2H5OH) and 1-propanol (C3H7OH) at 35C are 100 mmHg and 37.6 mmHg, respectively. Assume ideal behavior and calculate the partial pressures of ethanol and 1- propanol at 35C over a solution of ethanol in 1-propanol, in which the mole fraction of ethanol is 0.300

The vapor pressure of ethanol (C2H5OH) at 20C is 44 mmHg, and the vapor pressure of methanol (CH3OH) at the same temperature is 94 mmHg. A mixture of 30.0 g of methanol and 45.0 g of ethanol is prepared (and can be assumed to behave as an ideal solution). (a) Calculate the vapor pressure of methanol and ethanol above this solution at 20C. (b) Calculate the mole fraction of methanol and ethanol in the vapor above this solution at 20C. (c) Suggest a method for separating the two components of the solution

How many grams of urea [(NH2)2CO] must be added to 450 g of water to give a solution with a vapor pressure 2.50 mmHg less than that of pure water at 30C? (The vapor pressure of water at 30C is 31.8 mmHg.)

What are the boiling point and freezing point of a 2.47 m solution of naphthalene in benzene? (The boiling point and freezing point of benzene are 80.1C and 5.5C, respectively.)

An aqueous solution contains the amino acid glycine (NH2CH2COOH). Assuming that the acid does not ionize in water, calculate the molality of the solution if it freezes at 21.1C

Pheromones are compounds secreted by the females of many insect species to attract males. One of these compounds contains 80.78 percent C, 13.56 percent H, and 5.66 percent O. A solution of 1.00 g of this pheromone in 8.50 g of benzene freezes at 3.37C. What are the molecular formula and molar mass of the compound? (The normal freezing point of pure benzene is 5.50C.)

The elemental analysis of an organic solid extracted from gum arabic (a gummy substance used in adhesives, inks, and pharmaceuticals) showed that it contained 40.0 percent C, 6.7 percent H, and 53.3 percent O. A solution of 0.650 g of the solid in 27.8 g of the solvent diphenyl gave a freezing- point depression of 1.56C. Calculate the molar mass and molecular formula of the solid. (Kf for diphenyl is 8.00C/m.)

How many liters of the antifreeze ethylene glycol [CH2(OH)CH2(OH)] would you add to a car radiator containing 6.50 L of water if the coldest winter temperature in your area is 220C? Calculate the boiling point of this water-ethylene glycol mixture. (The density of ethylene glycol is 1.11 g/mL.)

A solution is prepared by condensing 4.00 L of a gas, measured at 27C and 748 mmHg pressure, into 58.0 g of benzene. Calculate the freezing point of this solution.

The molar mass of benzoic acid (C6H5COOH) determined by measuring the freezing-point depression in benzene is twice what we would expect for the molecular formula, C7H6O2. Explain this apparent anomaly.

A solution of 2.50 g of a compound having the empirical formula C6H5P in 25.0 g of benzene is observed to freeze at 4.3C. Calculate the molar mass of the solute and its molecular formula

What is the osmotic pressure (in atm) of a 1.36 M aqueous solution of urea [(NH2)2CO] at 22.0C?

A solution containing 0.8330 g of a polymer of unknown structure in 170.0 mL of an organic solvent was found to have an osmotic pressure of 5.20 mmHg at 25C. Determine the molar mass of the polymer.

A quantity of 7.480 g of an organic compound is dissolved in water to make 300.0 mL of solution. The solution has an osmotic pressure of 1.43 atm at 27C. The analysis of this compound shows that it contains 41.8 percent C, 4.7 percent H, 37.3 percent O, and 16.3 percent N. Calculate the molecular formula of the compound

A solution of 6.85 g of a carbohydrate in 100.0 g of water has a density of 1.024 g/mL and an osmotic pressure of 4.61 atm at 20.0C. Calculate the molar mass of the carbohydrate.

What are ion pairs? What effect does ion-pair formation have on the colligative properties of a solution? How does the ease of ion-pair formation depend on (a) charges on the ions, (b) size of the ions, (c) nature of the solvent (polar versus nonpolar), (d) concentration?

What is the vant Hoff factor? What information does it provide?

Which of the following aqueous solutions has (a) the higher boiling point, (b) the higher freezing point, and (c) the lower vapor pressure: 0.35 m CaCl2 or 0.90 m urea? Explain. Assume CaCl2 to undergo complete dissociation

Consider two aqueous solutions, one of sucrose (C12H22O11) and the other of nitric acid (HNO3). Both solutions freeze at 21.5C. What other properties do these solutions have in common?

Arrange the following solutions in order of decreasing freezing point: 0.10 m Na3PO4, 0.35 m NaCl, 0.20 m MgCl2, 0.15 m C6H12O6, 0.15 m CH3COOH

Arrange the following aqueous solutions in order of decreasing freezing point, and explain your reasoning: 0.50 m HCl, 0.50 m glucose, 0.50 m acetic acid

What are the normal freezing points and boiling points of the following solutions? (a) 21.2 g NaCl in 135 mL of water and (b) 15.4 g of urea in 66.7 mL of water

At 25C the vapor pressure of pure water is 23.76 mmHg and that of seawater is 22.98 mmHg. Assuming that seawater contains only NaCl, estimate its molal concentration.

Both NaCl and CaCl2 are used to melt ice on roads and sidewalks in winter. What advantages do these substances have over sucrose or urea in lowering the freezing point of water?

A 0.86 percent by mass solution of NaCl is called physiological saline because its osmotic pressure is equal to that of the solution in blood cells. Calculate the osmotic pressure of this solution at normal body temperature (37C). Note that the density of the saline solution is 1.005 g/mL.

The osmotic pressure of 0.010 M solutions of CaCl2 and urea at 25C are 0.605 atm and 0.245 atm, respectively. Calculate the vant Hoff factor for the CaCl2 solution

Calculate the osmotic pressure of a 0.0500 M MgSO4 solution at 25C. (Hint: See Table 12.3.)

What are colloids? Referring to Table 12.4, why is there no colloid in which both the dispersed phase and the dispersing medium are gases?

Describe how hydrophilic and hydrophobic colloids are stabilized in water.

Aqueous solutions A and B both contain urea at different concentrations. On standing exposed to air, the vapor pressure of A remains constant while that of B gradually decreases. (a) Which solution has a higher boiling point? (b) Eventually the two solutions have the same vapor pressure. Explain.

Water and methanol are miscible with each other but they are immiscible with octane (C8H18). Which of the following shows the correct picture when equal volumes of these three liquids are mixed in a test tube at 20C? Assume volumes to be additive. (The densities of the liquids are methanol: 0.792 g/mL; octane: 0.703 g/mL; water: 0.998 g/mL.) (a) (b) (c) (d)

Lysozyme is an enzyme that cleaves bacterial cell walls. A sample of lysozyme extracted from egg white has a molar mass of 13,930 g. A quantity of 0.100 g of this enzyme is dissolved in 150 g of water at 25C. Calculate the vapor-pressure lowering, the depression in freezing point, the elevation in boiling point, and the osmotic pressure of this solution. (The vapor pressure of water at 25C is 23.76 mmHg.)

Solutions A and B have osmotic pressures of 2.4 atm and 4.6 atm, respectively, at a certain temperature. What is the osmotic pressure of a solution prepared by mixing equal volumes of A and B at the same temperature?

A cucumber placed in concentrated brine (salt water) shrivels into a pickle. Explain.

Two liquids A and B have vapor pressures of 76 mmHg and 132 mmHg, respectively, at 25C. What is the total vapor pressure of the ideal solution made up of (a) 1.00 mole of A and 1.00 mole of B and (b) 2.00 moles of A and 5.00 moles of B?

Calculate the vant Hoff factor of Na3PO4 in a 0.40 m solution whose freezing point is 22.6C.

A 262-mL sample of a sugar solution containing 1.22 g of the sugar has an osmotic pressure of 30.3 mmHg at 35C. What is the molar mass of the sugar?

An aqueous solution of a 0.10 M monoprotic acid HA has an osmotic pressure of 3.22 atm at 25C. What is the percent ionization of the acid at this concentration?

Calculate the mass of naphthalene (C10H8) that must be added to 250 g of benzene (C6H6) to give a solution with a freezing point 2.00C below that of pure benzene

Consider the three mercury manometers shown here. One of them has 1 mL of water on top of the mercury, another has 1 mL of a 1 m urea solution on top of the mercury, and the third one has 1 mL of a 1 m NaCl solution placed on top of the mercury. Which of these solutions is in the tube labeled X, which is in Y, and which is in Z? XYZ

A forensic chemist is given a white powder for analysis. She dissolves 0.50 g of the substance in 8.0 g of benzene. The solution freezes at 3.9C. Can the chemist conclude that the compound is cocaine (C17H21NO4)? What assumptions are made in the analysis?

Time-release drugs have the advantage of releasing the drug to the body at a constant rate so that the drug concentration at any time is not too high as to have harmful side effects or too low as to be ineffective. A schematic diagram of a pill that works on this basis is shown below. Explain how it works. Rigid wall containing tiny holes Elastic impermeable membrane Drug Semipermeable membrane Saturated NaCl solution

A solution of 1.00 g of anhydrous aluminum chloride, AlCl3, in 50.0 g of water freezes at 21.11C. Does the molar mass determined from this freezing point agree with that calculated from the formula? Why?

Desalination is a process of removing dissolved salts from seawater. (a) Briefly describe how you would apply distillation and freezing for this purpose. (b) Desalination can also be accomplished by reverse osmosis, which uses high pressure to force water from a more concentrated solution to a less concentrated one. Assuming a sample of seawater is 0.50 M in NaCl, calculate the minimum pressure that needs to be applied for reverse osmosis at 25C. What is the main advantage of reverse osmosis over distillation and freezing? Pressure Semipermeable membrane Freshwater Seawater

Fish breathe the dissolved air in water through their gills. Assuming the partial pressures of oxygen and nitrogen in air to be 0.20 atm and 0.80 atm, respectively, calculate the mole fractions of oxygen and nitrogen in water at 298 K. Comment on your results. See Example 12.6 for Henrys law constants.

A protein has been isolated as a salt with the formula Na20P (this notation means that there are 20 Na1 ions associated with a negatively charged protein P202). The osmotic pressure of a 10.0-mL solution containing 0.225 g of the protein is 0.257 atm at 25.0C. (a) Calculate the molar mass of the protein from these data. (b) Calculate the actual molar mass of the protein.

A nonvolatile organic compound Z was used to make up two solutions. Solution A contains 5.00 g of Z dissolved in 100 g of water, and solution B contains 2.31 g of Z dissolved in 100 g of benzene. Solution A has a vapor pressure of 754.5 mmHg at the normal boiling point of water, and solution B has the same vapor pressure at the normal boiling point of benzene. Calculate the molar mass of Z in solutions A and B and account for the difference

Hydrogen peroxide with a concentration of 3.0 percent (3.0 g of H2O2 in 100 mL of solution) is sold in drugstores for use as an antiseptic. For a 10.0-mL 3.0 percent H2O2 solution, calculate (a) the oxygen gas produced (in liters) at STP when the compound undergoes complete decomposition and (b) the ratio of the volume of O2 collected to the initial volume of the H2O2 solution

State which of the alcohols listed in Problem 12.12 you would expect to be the best solvent for each of the following substances, and explain why: (a) I2, (b) KBr, (c) CH3CH2CH2CH2CH3.

Before a carbonated beverage bottle is sealed, it is pressurized with a mixture of air and carbon dioxide. (a) Explain the effervescence that occurs when the cap of the bottle is removed. (b) What causes the fog to form near the mouth of the bottle right after the cap is removed?

Iodine (I2) is only sparingly soluble in water (left photo). Yet upon the addition of iodide ions (for example, from KI), iodine is converted to the triiodide ion, which readily dissolves (right photo): I2(s) 1 I 2(aq) I 2 3 (aq) Describe the change in solubility of I2 in terms of the change in intermolecular forces.

Two beakers, one containing a 50-mL aqueous 1.0 M glucose solution and the other a 50-mL aqueous 2.0 M glucose solution, are placed under a tightly sealed bell jar at room temperature. What are the volumes in these two beakers at equilibrium?

In the apparatus shown here, what will happen if the membrane is (a) permeable to both water and the Na1 and Cl2 ions, (b) permeable to water and Na1 ions but not to Cl2 ions, (c) permeable to water but not to Na1 and Cl2 ions? 0.01 M NaCl 0.1 M NaCl Membrane

Explain why it is essential that fluids used in intravenous injections have approximately the same osmotic pressure as blood.

Concentrated hydrochloric acid is usually available at a concentration of 37.7 percent by mass. What is its molar concentration? (The density of the solution is 1.19 g/mL.)

Explain each of the following statements: (a) The boiling point of seawater is higher than that of pure water. (b) Carbon dioxide escapes from the solution when the cap is removed from a carbonated soft- drink bottle. (c) Molal and molar concentrations of dilute aqueous solutions are approximately equal. (d) In discussing the colligative properties of a solution (other than osmotic pressure), it is preferable to express the concentration in units of molality rather than in molarity. (e) Methanol (b.p. 65C) is useful as an antifreeze, but it should be removed from the car radiator during the summer season.

A mixture of NaCl and sucrose (C12H22O11) of combined mass 10.2 g is dissolved in enough water to make up a 250 mL solution. The osmotic pressure of the solution is 7.32 atm at 23C. Calculate the mass percent of NaCl in the mixture.

A 0.050 M hydrofluoric acid (HF) solution is 11 percent ionized at 25C. Calculate the osmotic pressure of the solution.

Shown here is a plot of vapor pressures of two liquids A and B at different concentrations at a certain temperature. Which of the following statements are false? (a) The solutions exhibit negative deviation from Raoults law. (b) A and B molecules attract each other more weakly than they do their own kind. (c) Hsoln is positive. (d) At XA 5 0.20, the solution has a higher boiling point than liquid B and a lower boiling point than liquid A. Pressure 0 PB o PA o XA 0.2 0.4 0.6 0.8 1.0

A 1.32-g sample of a mixture of cyclohexane (C6H12) and naphthalene (C10H8) is dissolved in 18.9 g of benzene (C6H6). The freezing point of the solution is 2.2C. Calculate the mass percent of the mixture. (See Table 12.2 for constants.)

How does each of the following affect the solubility of an ionic compound? (a) Lattice energy, (b) solvent (polar versus nonpolar), (c) enthalpies of hydration of cation and anion.

A solution contains two volatile liquids A and B. Complete the following table, in which the symbol indicates attractive intermolecular forces. Deviation from Attractive Forces Raoults Law DHsoln A A, B B . A B Negative Zero

The concentration of commercially available concentrated sulfuric acid is 98.0 percent by mass, or 18 M. Calculate the density and the molality of the solution.

The concentration of commercially available concentrated nitric acid is 70.0 percent by mass, or 15.9 M. Calculate the density and the molality of the solution

A mixture of ethanol and 1-propanol behaves ideally at 36C and is in equilibrium with its vapor. If the mole fraction of ethanol in the solution is 0.62, calculate its mole fraction in the vapor phase at this temperature. (The vapor pressures of pure ethanol and 1-propanol at 36C are 108 mmHg and 40.0 mmHg, respectively.)

For ideal solutions, the volumes are additive. This means that if 5 mL of A and 5 mL of B form an ideal solution, the volume of the solution is 10 mL. Provide a molecular interpretation for this observation. When 500 mL of ethanol (C2H5OH) are mixed with 500 mL of water, the final volume is less than 1000 mL. Why?

Ammonia (NH3) is very soluble in water, but nitrogen trichloride (NCl3) is not. Explain.

Aluminum sulfate [Al2(SO4)3] is sometimes used in municipal water treatment plants to remove undesirable particles. Explain how this process works.

Acetic acid is a weak acid that ionizes in solution as follows: CH3COOH(aq) CH3COO2(aq) 1 H1(aq) If the freezing point of a 0.106 m CH3COOH solution is 20.203C, calculate the percent of the acid that has undergone ionization.

Making mayonnaise involves beating oil into small droplets in water, in the presence of egg yolk. What is the purpose of the egg yolk? (Hint: Egg yolk contains lecithins, which are molecules with a polar head and a long nonpolar hydrocarbon tail.)

Acetic acid is a polar molecule and can form hydrogen bonds with water molecules. Therefore, it has a high solubility in water. Yet acetic acid is also soluble in benzene (C6H6), a nonpolar solvent that lacks Questions & Problems 557 the ability to form hydrogen bonds. A solution of 3.8 g of CH3COOH in 80 g C6H6 has a freezing point of 3.5C. Calculate the molar mass of the solute and suggest what its structure might be. (Hint: Acetic acid molecules can form hydrogen bonds between themselves.)

A 2.6-L sample of water contains 192 g of lead. Does this concentration of lead exceed the safety limit of 0.050 ppm of lead per liter of drinking water? [Hint: 1 g 5 1 3 1026 g. Parts per million (ppm) is defined as (mass of component/mass of solution) 3 106 .]

Certain fishes in the Antarctic Ocean swim in water at about 22C. (a) To prevent their blood from freezing, what must be the concentration (in molality) of the blood? Is this a reasonable physiological concentration? (b) In recent years scientists have discovered a special type of protein in these fishes blood which, although present in quite low concentrations (# 0.001 m), has the ability to prevent the blood from freezing. Suggest a mechanism for its action.

As we know, if a soft drink can is shaken and then opened, the drink escapes violently. However, if after shaking the can we tap it several times with a metal spoon, no such explosion of the drink occurs. Why?

Why are ice cubes (for example, those you see in the trays in the freezer of a refrigerator) cloudy inside?

Two beakers are placed in a closed container. Beaker A initially contains 0.15 mole of naphthalene (C10H8) in 100 g of benzene (C6H6) and beaker B initially contains 31 g of an unknown compound dissolved in 100 g of benzene. At equilibrium, beaker A is found to have lost 7.0 g of benzene. Assuming ideal behavior, calculate the molar mass of the unknown compound. State any assumptions made

At 27C, the vapor pressure of pure water is 23.76 mmHg and that of an urea solution is 22.98 mmHg. Calculate the molality of solution.

An example of the positive deviation shown in Figure 12.8(a) is a solution made of acetone (CH3COCH3) and carbon disulfide (CS2). (a) Draw Lewis structures of these molecules. Explain the deviation from ideal behavior in terms of intermolecular forces. (b) A solution composed of 0.60 mole of acetone and 0.40 mole of carbon disulfide has a vapor pressure of 615 mmHg at 35.2C. What would be the vapor pressure if the solution behaved ideally? The vapor pressure of the pure solvents at the same temperature are: acetone: 349 mmHg; carbon disulfide: 501 mmHg. (c) Predict the sign of Hsoln.

Liquids A (molar mass 100 g/mol) and B (molar mass 110 g/mol) form an ideal solution. At 55C, A has a vapor pressure of 95 mmHg and B has a vapor pressure of 42 mmHg. A solution is prepared by mixing equal masses of A and B. (a) Calculate the mole fraction of each component in the solution. (b) Calculate the partial pressures of A and B over the solution at 55C. (c) Suppose that some of the vapor described in (b) is condensed to a liquid in a separate container. Calculate the mole fraction of each component in this liquid and the vapor pressure of each component above this liquid at 55C.

A very long pipe is capped at one end with a semipermeable membrane. How deep (in meters) must the pipe be immersed into the sea for freshwater to begin to pass through the membrane? Assume the water to be at 20C and treat it as a 0.70 M NaCl solution. The density of seawater is 1.03 g/cm3 and the acceleration due to gravity is 9.81 m/s2 .

Two beakers, 1 and 2, containing 50 mL of 0.10 M urea and 50 mL of 0.20 M urea, respectively, are placed under a tightly sealed container (see Figure 12.12) at 298 K. Calculate the mole fraction of urea in the solutions at equilibrium. Assume ideal behavior.

A mixture of liquids A and B exhibits ideal behavior. At 84C, the total vapor pressure of a solution containing 1.2 moles of A and 2.3 moles of B is 331 mmHg. Upon the addition of another mole of B to the solution, the vapor pressure increases to 347 mmHg. Calculate the vapor pressures of pure A and B at 84C.

Use Henrys law and the ideal gas equation to prove the statement that the volume of a gas that dissolves in a given amount of solvent is independent of the pressure of the gas. (Hint: Henrys law can be modified as n 5 kP, where n is the number of moles of the gas dissolved in the solvent.)

(a) Derive the equation relating the molality (m) of a solution to its molarity (M) m 5 M d 2 Mm 1000 where d is the density of the solution (g/mL) and m is the molar mass of the solute (g/mol). (Hint: Start by expressing the solvent in kilograms in terms of the difference between the mass of the solution and the mass of the solute.) (b) Show that, for dilute aqueous solutions, m is approximately equal to M.

At 298 K, the osmotic pressure of a glucose solution is 10.50 atm. Calculate the freezing point of the solution. The density of the solution is 1.16 g/mL

A student carried out the following procedure to measure the pressure of carbon dioxide in a soft drink bottle. First, she weighed the bottle (853.5 g). Next, she carefully removed the cap to let the CO2 gas escape. She then reweighed the bottle with the cap (851.3 g). Finally, she measured the volume of the soft drink (452.4 mL). Given that Henrys law constant for CO2 in water at 25C is 3.4 3 1022 mol/L ? atm, calculate the pressure of CO2 in the original bottle. Why is this pressure only an estimate of the true value?

Valinomycin is an antibiotic. It functions by binding K1 ions and transporting them across the membrane into cells to offset the ionic balance. The molecule is represented here by its skeletal structure in which the end of each straight line corresponds to a carbon atom (unless a N or an O atom is shown at the end of the line). There are as many H atoms attached to each C atom as necessary to give each C atom a total of four bonds. Use the like dissolves like guideline to explain its function. (Hint: The CH3 groups at the two ends of the Y shape are nonpolar.) N HN H H N O O O O O O O O O O O O O O O O O O NH NH HN

Often the determination of the molar mass of a compound by osmotic pressure measurement is carried out at several different concentrations to get a more reliable average value. From the following data for the osmotic pressure of poly(methyl methacrylate) in toluene at 25C, determine graphically the molar mass of the polymer. [Hint: Rearrange Equation (12.8) so that is expressed in terms of c, which is the number of grams of the solute per liter of solution.] (atm) 8.40 3 1.72 3 2.52 3 3.23 3 7.75 3 1024 1023 1023 1023 1023 c (g/L) 8.10 12.31 15.00 18.17 28.05

Here is an after-dinner trick. With guests still sitting at the table, the host provided each of them with a glass of water containing an ice cube floating on top and a piece of string about 23 in. in length. He then asked them to find a way to lift the ice cube without touching it by hand or using any other objects such as a spoon or fork. Explain how this task can be accomplished. (Hint: The table had not been cleared so the salt and pepper shakers were still there.)

The molecule drawn here has shown promise as an agent for cleaning up oil spills in water. Instead of dispersing the oil into water as soap molecules would do (see Figures 12.19 and 12.20), these molecules bind with the oil to form a gel, which can be easily separated from the body of water. Suggest an explanation for the ability of this compound to remove oil from water. O O O O O OHOH H15C7 C7H15

The Henrys law constant of oxygen in water at 25C is 1.3 3 1023 mol/L ? atm. Calculate the molarity of oxygen in water under 1 atmosphere of air. Comment on the prospect for our survival without hemoglobin molecules. (Recall from previous problems that the total volume of blood in an adult human is about 5 L.)

The diagram shows the vapor pressure curves for pure benzene and a solution of a nonvolatile solute in benzene. Estimate the molality of the benzene solution. t (8C) P (atm) 75 1.0 80 85

A common misconception is that adding salt to the water used to cook spaghetti will decrease the cooking time, presumably because it increases the boiling point of the water. Calculate the boiling point of a typical salted water solution used to cook spaghetti. Do you think this increase in temperature will make much difference in the cooking time for spaghetti?

Estimate the volume of the oil droplet that would be formed by the compound sodium stearate shown in Figure 12.19

The diagram here shows the vapor pressure curves of two liquids A and B and a solution of the two liquids. Given that A is more volatile than B, match the curves with the pure liquids and the solution.

Problem 1E Explain why drinking seawater results in dehydration.

Which compound do you expect to be soluble in octane (C8H18)? a) CH3OH b) CBr4 c) H2O d) NH3

Problem 2E What is a solution? What are the solute and solvent?

Problem 3E What does it mean to say that a substance is soluble in another substance? Which units are used in reporting solubility?

Problem 2SAQ An aqueous solution is saturated in both potassium chlorate and carbon dioxide gas at room temperature. What happens when the solution is warmed to 85 °C? a) Potassium chlorate precipitates out of solution. b) Carbon dioxide bubbles out of solution. c) Potassium chlorate precipitates out of solution and carbon dioxide bubbles out of solution. d) Nothing happens; all of the potassium chloride and the carbon dioxide remain dissolved in solution.

A 500.0 ml sample of pure water is allowed to come to equilibrium with pure oxygen gas at a pressure of 755 mmHg. What mass of oxygen gas dissolves in the water? (The Henry’s law constant for oxygen gas is 1.3 x 10-3 M/atm.) a) 15.7 g b) 6.5 x 10-3 g c) 0.041 g d) 0.021 g

Problem 4E Why do two ideal gases thoroughly mix when combined? What drives the mixing?

Problem 4SAQ A potassium bromide solution is 7.55 % potassium bromide by mass and its density is 1.03 g/mL. What mass of potassium bromide is contained in 35.8 mL of the solution? a) 2.78 g b) 2.70 g c) 4.88 g d) 2.62 g

Problem 5E What is entropy? Why is entropy important in discussing the formation of solutions?

A solution contains 22.4 g glucose (C6H12O6) dissolved in 0.500 L of water. What is the molality of the solution? ( Assume a density of 1.00 g/mL for water.) a) 0.238 m b) 44.8 m c) 0.249 m d) 4.03 m

Problem 6E What kinds of intermolecular forces are involved in solution formation?

A sodium nitrate solution is 12.5% NaNO3 by mass and has a density of 1.02 g/mL. Calculate the molarity of the solution. a) 1.44 M b) 12.8 M c) 6.67 M d) 1.50 M

Problem 7E Explain how the relative strengths of solute–solute interactions, solvent–solvent interactions, and solvent–solute interactions affect solution formation.

Determine the vapor pressure of an aqueous ethylene glycol \(\left(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}\right)\) solution that is 14.8 % \(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}\) by mass. The vapor pressure of pure water at \(25^{\circ} \mathrm{C}\) is 23.8 torr. a) 3.52 torr b) 22.7 torr c) 1.14 torr d) 20.3 torr

Problem 8E What does the statement like dissolves like mean with respect to solution formation?

Problem 8SAQ A solution contains a mixture of substance A and substance B, both of which are volatile. The mole fraction of substance A is 0.35. At 32 °C the vapor pressure of pure A is 87 mmHg and the vapor pressure of pure B is 122 mmHg. What is the total vapor pressure of the solution at this temperature? a) 110 mmHg b) 209 mmHg c) 99.3 mmHg d) 73.2 mmHg

Problem 9E What are three steps involved in evaluating the enthalpy changes associated with solution formation?

What mass of glucose (C6H12O6) should be dissolved in 10.0 kg of water to obtain a solution with a freezing point of -4.2 °C? a) 0.023 kg b) 4.1 kg c) 0.41 kg d) 14.1 kg

What is the heat of hydration (hydration)? How does the enthalpy of solution depend on the relative magnitudes of solute and hydration?

Which of these aqueous solutions has the highest boiling point? a) 1.25 M C6H12O6 b) 1.25 M KNO3 c) 1.25 M Ca(NO3)2 d) None of the above (they all have the same boiling point)

Problem 11E Explain dynamic equilibrium with respect to solution formation. What is a saturated solution? An unsaturated solution? A supersaturated solution?

The osmotic pressure of a solution containing 22.7 mg of an unknown protein in 50.0 mL of solution is 2.88 mmHg at 25 °C. Determine the molar mass of the protein. a) 246 g/mol b) 3.85 g/mol c) 2.93 x 103 g/mol d) 147 g/mol

Problem 12E How does the solubility of a solid in a liquid depend on temperature? How is this temperature dependence exploited to purify solids through recrystallization?

The enthalpy of solution for NaOH is -44.46 kJ>mol. What can you conclude about the relative magnitudes of the absolute values of solute and hydration, where solute is the heat associated with separating the solute particles and hydration is the heat associated with dissolving the solute particles in water? d) None of the above (nothing can be concluded about the relative magnitudes)

Problem 13E How does the solubility of a gas in a liquid depend on temperature? How does this temperature dependence affect the amount of oxygen available for fish and other aquatic animals?

A 2.4 m aqueous solution of an ionic compound with the formula MX2 has a boiling point of 103.4 °C. Calculate the van’t Hoff factor (i) for MX2 at this concentration. a) 2.8 b) 83 c) 0.73 d) 1.0

Problem 14E How does the solubility of a gas in a liquid depend on pressure? How does this pressure dependence account for the bubbling that occurs upon opening a can of soda?

Problem 14SAQ A solution is an equimolar mixture of two volatile components A and B. Pure A has a vapor pressure of 50 torr and pure B has a vapor pressure of 100 torr. The vapor pressure of the mixture is 85 torr. What can you conclude about the relative strengths of the intermolecular forces between particles of A and B ( relative to those between particles of A and those between particles of B)? a) The intermolecular forces between particles A and B are weaker than those between particles of A and those between particles of B. b) The intermolecular forces between particles A and B are stronger than those between particles of A and those between particles of B. c) The intermolecular forces between particles A and B are the same as those between particles of A and those between particles of B. d) Nothing can be concluded about the relative strengths of intermolecular forces from this observation.

Problem 15E What is Henry’s law? For what kinds of calculations is Henry’s law useful?

An aqueous solution is in equilibrium with a gaseous mixture containing an equal number of moles of oxygen, nitrogen, and helium. Rank the relative concentrations of each gas in the aqueous solution from highest to lowest.

Problem 16E What are the common units for expressing solution concentration?

Problem 17E How are parts by mass and parts by volume used in calculations?

Problem 18E What is the effect of a nonvolatile solute on the vapor pressure of a liquid? Why is the vapor pressure of a solution different from the vapor pressure of the pure liquid solvent?

What is Raoult’s law? For what kind of calculations is Raoult’s law useful?

Problem 20E Explain the difference between an ideal and a nonideal solution.

Problem 21E What is the effect on vapor pressure of a solution with particularly strong solute–solvent interactions? With particularly weak solute–solvent interactions?

Problem 22E Explain why the lower vapor pressure for a solution containing a nonvolatile solute results in a higher boiling point and lower melting point compared to the pure solvent.

What are colligative properties?

Problem 24E What is osmosis? What is osmotic pressure?

Problem 25E Explain the meaning of the van’t Hoff factor and its role in determining the colligative properties of solutions containing ionic solutes.

Problem 26E Describe a colloidal dispersion. What is the difference between a colloidal dispersion and a true solution?

Problem 27E What is the Tyndall effect and how can it be used to help identify colloidal dispersions?

Problem 28E What keeps the particles in a colloidal dispersion from coalescing?

Pick an appropriate solvent from Table 12.3 to dissolve each substance. State the kind of intermolecular forces that would occur between the solute and solvent in each case. a. isopropyl alcohol (polar, contains an OH group) b. sodium chloride (ionic) c. vegetable oil (nonpolar) d. sodium nitrate (ionic)

Pick an appropriate solvent from Table 12.3 to dissolve each substance. State the kind of intermolecular forces that would occur between the solute and solvent in each case. a. motor oil (nonpolar) b. ethanol (polar, contains an OH group) c. lard (nonpolar) d. potassium chloride (ionic)

Which molecule would you expect to be more soluble in water, CH3CH2CH2OH or HOCH2CH2CH2OH?

Which molecule would you expect to be more soluble in water, CCl4 or CH2Cl2?

For each compound, would you expect greater solubility in water or in hexane? Indicate the kinds of intermolecular forces that occur between the solute and the solvent in which the molecule is most soluble.

For each compound, would you expect greater solubility in water or in hexane? Indicate the kinds of intermolecular forces that would occur between the solute and the solvent in which the molecule is most soluble.

When ammonium chloride (NH4Cl) is dissolved in water, the solution becomes colder. a. Is the dissolution of ammonium chloride endothermic or exothermic? b. What can you conclude about the relative magnitudes of the lattice energy of ammonium chloride and its heat of hydration? c. Sketch a qualitative energy diagram similar to Figure 12.7 for the dissolution of NH4Cl. d. Why does the solution form? What drives the process?

When lithium iodide (LiI) is dissolved in water, the solution becomes hotter. a. Is the dissolution of lithium iodide endothermic or exothermic? b. What can you conclude about the relative magnitudes of the lattice energy of lithium iodide and its heat of hydration? c. Sketch a qualitative energy diagram similar to Figure 12.7 for the dissolution of LiI. d. Why does the solution form? What drives the process?

Problem 37E Silver nitrate has a lattice energy of -820 kJ/mol and a heat of solution of -22.6 Kj/mol . Calculate the heat of hydration for silver nitrate.

Use the data to calculate the heats of hydration of lithium chloride and sodium chloride. Which of the two cations, lithium or sodium, has stronger ion–dipole interactions with water? Why?

Lithium iodide has a lattice energy of -7.3 x 102 kJ/mol and a heat of hydration of -793 kJ/mol. Find the heat of solution for lithium iodide and determine how much heat is evolved or absorbed when 15.0 g of lithium iodide completely dissolves in water.

Potassium nitrate has a lattice energy of -163.8 kcal/mol and a heat of hydration of -155.5 kcal>mol. How much potassium nitrate has to dissolve in water to absorb 1.00 x 102 kJ of heat?

A solution contains 25 g of NaCl per 100.0 g of water at 25 oC. Is the solution unsaturated, saturated, or supersaturated? ( Use Figure 12.11 .)

A solution contains 32 g of \(\mathrm{KNO}_{3}\) per 100.0 g of water at \(25^{\circ} \mathrm{C}\). Is the solution unsaturated, saturated, or supersaturated? (Use Figure 12.11.)

A KNO3 solution containing 45 g of KNO3 per 100.0 g of water is cooled from 40 oC to 0 oC. What happens during cooling? ( Use Figure 12.11 .)

A KCl solution containing 42 g of KCl per 100.0 g of water is cooled from 60 oC to 0 oC. What happens during cooling? ( Use Figure 12.11 .)

Problem 45E Some laboratory procedures involving oxygen-sensitive reactants or products call for using water that has been boiled (and then cooled). Explain.

Problem 46E A person preparing a fish tank fills the tank with water that has been boiled (and then cooled). When the person puts fish into the tank, they die. Explain.

Scuba divers breathing air at increased pressure can suffer from nitrogen narcosis—a condition resembling drunkenness—when the partial pressure of nitrogen exceeds about 4 atm. What property of gas/water solutions causes this to happen? How can a diver reverse this effect?

Problem 48E Scuba divers breathing air at increased pressure can suffer from oxygen toxicity—too much oxygen in their bloodstream— when the partial pressure of oxygen exceeds about 1.4 atm. What happens to the amount of oxygen in a diver’s bloodstream when he or she breathes oxygen at elevated pressures? How can this be reversed?

Problem 49E Calculate the mass of nitrogen dissolved at room temperature in an 80.0 L home aquarium. Assume a total pressure of 1.0 atm and a mole fraction for nitrogen of 0.78.

Use Henry’s law to determine the molar solubility of helium at a pressure of 1.0 atm and 25 oC.

Problem 51E An aqueous NaCl solution is made using 112 g of NaCl diluted to a total solution volume of 1.00 L. Calculate the molarity, molality, and mass percent of the solution. (Assume a density of 1.08 g/mL for the solution.)

An aqueous KNO3 solution is made using 72.5 g of KNO3 diluted to a total solution volume of 2.00 L. Calculate the molarity, molality, and mass percent of the solution. (Assume a density of 1.05 g/mL for the solution.)

Problem 53E To what volume should you dilute 50.0 mL of a 5.00 M KI solution so that 25.0 mL of the diluted solution contains 3.05 g of KI?

To what volume should you dilute 125 mL of an 8.00 M CuCl2 solution so that 50.0 mL of the diluted solution contains 4.67 g CuCl2?

Silver nitrate solutions are often used to plate silver onto other metals. What is the maximum amount of silver (in grams) that can be plated out of 4.8 L of an AgNO3 solution containing 3.4% Ag by mass? Assume that the density of the solution is 1.01 g/mL.

Problem 56E A dioxin-contaminated water source contains 0.085% dioxin by mass. How much dioxin is present in 2.5 L of this water? Assume a density of 1.00 g/mL.

A hard water sample contains 0.0085% \(\mathrm{Ca}\) by mass (in the form of \(\mathrm{Ca}^{2+}\) ions). How much water (in grams) contains \(1.2 \mathrm{~g}\) of \(\mathrm{Ca}\)? (\(1.2 \mathrm{g}\) of \(\mathrm{Ca}\) is the recommended daily allowance of calcium for those between 19 and 24 years old.)

Problem 58E Lead is a toxic metal that affects the central nervous system. A Pb-contaminated water sample contains 0.0011% Pb by mass. How much of the water (in mL) contains 150 mg of Pb? (Assume a density of 1.0 g/mL.)

You can purchase nitric acid in a concentrated form that is 70.3% HNO3 by mass and has a density of 1.41 g/mL . Describe exactly how you would prepare 1.15 L of 0.100 M HNO3 from the concentrated solution.

Problem 60E You can purchase hydrochloric acid in a concentrated form that is 37.0% HCl by mass and that has a density of 1.20 g/mL. Describe exactly how to prepare 2.85 L of 0.500 M HCl from the concentrated solution.

Describe how to prepare each solution from the dry solute and the solvent. a. 1.00 x 102 mL of 0.500 M KCl b. 1.00 x 102 g of 0.500 m KCl c. 1.00 x 102 g of 5.0% KCl solution by mass

Describe how to prepare each solution from the dry solute and the solvent. a. 125 mL of 0.100 M NaNO3 b. 125 g of 0.100 m NaNO3 c. 125 g of 1.0% NaNO3 solution by mass

A solution is prepared by dissolving 28.4 g of glucose (C6H12O6) in 355 g of water. The final volume of the solution is 378 mL. For this solution, calculate the concentration in each unit. a. molarity b. molality c. percent by mass d. mole fraction e. mole percent

A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0 mL of water at 25 oC. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, calculate the concentration in each unit. a. molarity b. molality c. percent by mass d. mole fraction e. mole percent

Problem 65E Household hydrogen peroxide is an aqueous solution containing 3.0% hydrogen peroxide by mass. What is the molarity of this solution? (Assume a density of 1.01 g/mL.)

Problem 66E One brand of laundry bleach is an aqueous solution containing 4.55% sodium hypochlorite (NaOCl) by mass. What is the molarity of this solution? (Assume a density of 1.02 g/mL.)

Problem 67E An aqueous solution contains 36% HCl by mass. Calculate the molality and mole fraction of the solution.

Problem 68E An aqueous solution contains 5.0% NaCl by mass. Calculate the molality and mole fraction of the solution.

Problem 69E A beaker contains 100.0 mL of pure water. A second beaker contains 100.0 mL of seawater. The two beakers are left side by side on a lab bench for 1 week. At the end of the week, the liquid level in both beakers has decreased. However, the level has decreased more in one of the beakers than in the other. Which one and why?

Which solution has the highest vapor pressure? a. 20.0 g of glucose (C6H12O6) in 100.0 mL of water b. 20.0 g of sucrose (C12H22O11) in 100.0 mL of water c. 10.0 g of potassium acetate KC2H3O2 in 100.0 mL of water

Calculate the vapor pressure of a solution containing 24.5 g of glycerin (C3H8O3) in 135 mL of water at 30.0 oC. The vapor pressure of pure water at this temperature is 31.8 torr. Assume that glycerin is not volatile and dissolves molecularly (i.e., it is not ionic), and use a density of 1.00 g/mL for the water

A solution contains naphthalene (C10H8) dissolved in hexane (C6H14) at a concentration of 12.35% naphthalene by mass. Calculate the vapor pressure at 25 oC of hexane above the solution. The vapor pressure of pure hexane at 25 oC is 151 torr.

A solution contains 50.0 g of heptane (C7H16) and 50.0 g of octane (C8H18) at 25 oC. The vapor pressures of pure heptane and pure octane at 25 oC are 45.8 torr and 10.9 torr, respectively. Assuming ideal behavior, answer the following:

Problem 74E A solution contains a mixture of pentane and hexane at room temperature. The solution has a vapor pressure of 258 torr. Pure pentane and hexane have vapor pressures of 425 torr and 151 torr, respectively, at room temperature. What is the mole fraction composition of the mixture? (Assume ideal behavior.)

A solution contains 4.08 g of chloroform (CHCl3) and 9.29 g of acetone (CH3COCH3). The vapor pressures at 35 oC of pure chloroform and pure acetone are 295 torr and 332 torr, respectively. Assuming ideal behavior, calculate the vapor pressures of each of the components and the total vapor pressure above the solution. The experimentally measured total vapor pressure of the solution at 35 oC was 312 torr. Is the solution ideal? If not, what can you say about the relative strength of chloroform–acetone interactions compared to the acetone–acetone and chloroform–chloroform interactions?

A solution of methanol and water has a mole fraction of water of 0.312 and a total vapor pressure of 211 torr at 39.9 oC. The vapor pressures of pure methanol and pure water at this temperature are 256 torr and 55.3 torr, respectively. Is the solution ideal? If not, what can you say about the relative strengths of the solute–solvent interactions compared to the solute–solute and solvent–solvent interactions?

A glucose solution contains 55.8 g of glucose (C6H12O6) in 455 g of water. Determine the freezing point and boiling point of the solution.

An ethylene glycol solution contains 21.2 g of ethylene glycol (C2H6O2) in 85.4 mL of water. Determine the freezing point and boiling point of the solution. (Assume a density of 1.00 g/mL for water.)

Calculate the freezing point and melting point of a solution containing 10.0 g of naphthalene (C10H8) in 100.0 mL of benzene. Benzene has a density of 0.877 g/cm3.

Calculate the freezing point and melting point of a solution containing 7.55 g of ethylene glycol (C2H6O2) in 85.7 mL of ethanol. Ethanol has a density of 0.789 g/cm3.

An aqueous solution containing 17.5 g of an unknown molecular (nonelectrolyte) compound in 100.0 g of water has a freezing point of -1.8 oC. Calculate the molar mass of the unknown compound.

An aqueous solution containing 35.9 g of an unknown molecular (nonelectrolyte) compound in 150.0 g of water has a freezing point of \(-1.3\ ^{\circ}\mathrm{C}\). Calculate the molar mass of the unknown compound.

Calculate the osmotic pressure of a solution containing \(24.6 \mathrm{~g}\) of glycerin \(\left(\mathrm{C}_3 \mathrm{H}_8 \mathrm{O}_3\right)\) in \(250.0 \mathrm{~mL}\) of solution at \(298 \mathrm{~K}\).

What mass of sucrose (C12H22O11) would you combine with 5.00 x 102 g of water to make a solution with an osmotic pressure of 8.55 atm at 298 K? (Assume a density of 1.0 g/mL for the solution.)

A solution containing 27.55 mg of an unknown protein per 25.0 mL solution was found to have an osmotic pressure of 3.22 torr at 25 >oC. What is the molar mass of the protein?

Calculate the osmotic pressure of a solution containing 18.75 mg of hemoglobin in 15.0 mL of solution at 25 oC. The molar mass of hemoglobin is 6.5 x 104 g/mol.

Calculate the freezing point and boiling point of each aqueous solution, assuming complete dissociation of the solute. a. 0.100 m K2S b. 21.5 g of CuCl2 in 4.50 x 102 g water c. 5.5% NaNO3 by mass (in water)

Calculate the freezing point and boiling point in each solution, assuming complete dissociation of the solute. a. 10.5 g FeCl3 in 1.50 x 102 g water b. 3.5% KCl by mass (in water) c. 0.150 m MgF2

Problem 89E What mass of salt (NaCl) should you add to 1.00 L of water in an ice cream maker to make a solution that freezes at -10.0 °C? Assume complete dissociation of the NaCl and density of 1.00 g/mL for water.

Determine the required concentration (in percent by mass) for an aqueous ethylene glycol (C2H6O2) solution to have a boiling point of 104.0 °C.

Use the van’t Hoff factors in Table 12.9 to calculate each colligative property: a. the melting point of a 0.100 m iron(III) chloride solution b. the osmotic pressure of a 0.085 M potassium sulfate solution at 298 K c. the boiling point of a 1.22% by mass magnesium chloride solution

Assuming the van’t Hoff factors in Table 12.9 , calculate the mass of solute required to make each aqueous solution: a. a sodium chloride solution containing 1.50 x 102 g of water that has a melting point of -1.0 oC b. 2.50 x 102 mL of a magnesium sulfate solution that has an osmotic pressure of 3.82 atm at 298 K c. an iron(III) chloride solution containing 2.50 x 102 g of water that has a boiling point of 102 oC

A 1.2 m aqueous solution of an ionic compound with the formula MX2 has a boiling point of 101.4 °C. Calculate the van’t Hoff factor ( i ) for MX2 at this concentration.

A 0.95 m aqueous solution of an ionic compound with the formula MX has a freezing point of \(-3.0 \ ^\circ C\). Calculate the van’t Hoff factor (i) for MX at this concentration.

A 0.100 M ionic solution has an osmotic pressure of 8.3 atm at 25 oC. Calculate the van’t Hoff factor ( i ) for this solution.

Calculate the vapor pressure at \(25 ^\circ C\) of an aqueous solution that is 5.50% NaCl by mass. (Assume complete dissociation of the solute.)

A solution contains 8.92 g of KBr in 500.0 mL of solution and has an osmotic pressure of 6.97 atm at 25 oC. Calculate the van’t Hoff factor ( i ) for KBr at this concentration.

An aqueous CaCl2 solution has a vapor pressure of 81.6 mmHg at 50 oC. The vapor pressure of pure water at this temperature is 92.6 mmHg. What is the concentration of CaCl2 in mass percent? (Assume complete dissociation of the solute.)

The solubility of carbon tetrachloride \(\left(\mathrm{CCl}_{4}\right)\) in water at \(25\ ^{\circ}\mathrm{C}\) is 1.2 g/L. The solubility of chloroform \(\left(\mathrm{CHCl}_{3}\right)\) at the same temperature is 10.1 g/L. Why is chloroform almost ten times more soluble in water than carbon tetrachloride?

The solubility of phenol in water at 25 oC is 8.7 g/L. The solubility of naphthol at the same temperature is only 0.074 g/L. Examine the structures of phenol and naphthol shown here and explain why phenol is so much more soluble than naphthol.

Potassium perchlorate (KClO4) has a lattice energy of -599 kJ/mol and a heat of hydration of -548 kJ/mol. Find the heat of solution for potassium perchlorate and determine the temperature change that occurs when 10.0 g of potassium perchlorate is dissolved with enough water to make 100.0 mL of solution. (Assume a heat capacity of 4.05 J/g oC for the solution and a density of 1.05 g/mL.)

Sodium hydroxide (NaOH) has a lattice energy of -887 kJ/mol and a heat of hydration of -932 kJ/mol. How much solution could be heated to boiling by the heat evolved by the dissolution of 25.0 g of NaOH? (For the solution, assume a heat capacity of 4.0 J/g oC, an initial temperature of 25.0 oC, a boiling point of 100.0 oC, and a density of 1.05 g/mL.)

A saturated solution forms when 0.0537 L of argon, at a pressure of 1.0 atm and temperature of 25 oC, is dissolved in 1.0 L of water. Calculate the Henry’s law constant for argon.

A gas has a Henry’s law constant of 0.112 M>atm. What total volume of solution is needed to completely dissolve 1.65 L of the gas at a pressure of 725 torr and a temperature of 25 oC?

Problem 105E The Safe Drinking Water Act (SDWA) sets a limit for mercury—a toxin to the central nervous system—at 0.0020 ppm by mass. Water suppliers must periodically test their water to ensure that mercury levels do not exceed this limit. Suppose water becomes contaminated with mercury at twice the legal limit (0.0040 ppm). How much of this water would a person have to consume to ingest 50.0 mg of mercury?

Problem 106E Water softeners often replace calcium ions in hard water with sodium ions. Since sodium compounds are soluble, the presence of sodium ions in water does not cause the white, scaly residues caused by calcium ions. However, calcium is more beneficial to human health than sodium because calcium is a necessary part of the human diet, while high levels of sodium intake are linked to increases in blood pressure. The U.S. Food and Drug Administration (FDA) recommends that adults ingest less than 2.4 g of sodium per day. How many liters of softened water, containing a sodium concentration of 0.050% sodium by mass, would a person have to consume to exceed the FDA recommendation? (Assume a water density of 1.0 g/mL.)

An aqueous solution contains 12.5% \(\mathrm{NaCl}\) by mass. What mass of water (in grams) is contained in \(2.5 \mathrm{~L}\) of the vapor above this solution at \(55^{\circ} \mathrm{C}\)? The vapor pressure of pure water at \(55^{\circ} \mathrm{C}\) is 118 torr. (Assume complete dissociation of \(\mathrm{NaCl}\).)

The vapor above an aqueous solution contains 19.5 mg water per liter at 25 oC. Assuming ideal behavior, what is the concentration of the solute within the solution in mole percent?

What is the freezing point of an aqueous solution that boils at 106.5 oC?

What is the boiling point of an aqueous solution that has a vapor pressure of 20.5 torr at 25 oC? (Assume a nonvolatile solute.)

An isotonic solution contains 0.90% NaCl mass to volume. Calculate the percent mass to volume for isotonic solutions containing each solute at 25 oC. Assume a van’t Hoff factor of 1.9 for all ionic solutes. a. KCl b. NaBr c. glucose (C6H12O6)

Magnesium citrate, Mg3 (C6H5O7)2 belongs to a class of laxatives called hyperosmotics , which cause rapid emptying of the bowel. When a concentrated solution of magnesium citrate is consumed, it passes through the intestines, drawing water and promoting diarrhea, usually within 6 hours. Calculate the osmotic pressure of a magnesium citrate laxative solution containing 28.5 g of magnesium citrate in 235 mL of solution at 37 oC (approximate body temperature). Assume complete dissociation of the ionic compound.

Problem 113E A solution is prepared from 4.5701 g of magnesium chloride and 43.238 g of water. The vapor pressure of water above this solution is 0.3624 atm at 348.0 K. The vapor pressure of pure water at this temperature is 0.3804 atm. Find the value of the van’t Hoff factor ( i) for magnesium chloride in this solution.

When HNO2 is dissolved in water it partially dissociates according to the equation HNO2 ? H- + NO2-. A solution is prepared that contains 7.050 g of HNO2 in 1.000 kg of water. Its freezing point is 20.2929 oC. Calculate the fraction of HNO2 that has dissociated.

Problem 115E A solution of a nonvolatile solute in water has a boiling point of 375.3 K. Calculate the vapor pressure of water above this solution at 338 K. The vapor pressure of pure water at this temperature is 0.2467 atm.

The density of a 0.438 M solution of potassium chromate (K2CrO4) at 298 K is 1.063 g/mL. Calculate the vapor pressure of water above the solution. The vapor pressure of pure water at this temperature is 0.0313 atm. (Assume complete dissociation of the solute.)

The vapor pressure of carbon tetrachloride, CCl4, is 0.354 atm and the vapor pressure of chloroform, CHCl3, is 0.526 atm at 316 K. A solution is prepared from equal masses of these two compounds at this temperature. Calculate the mole fraction of the chloroform in the vapor above the solution. If the vapor above the original solution is condensed and isolated into a separate flask, what would the vapor pressure of chloroform be above this new solution?

Problem 118E Distillation is a method of purification based on successive separations and recondensations of vapor above a solution. Use the result of the previous problem to calculate the mole fraction of chloroform in the vapor above a solution obtained by three successive separations and condensations of the vapors above the original solution of carbon tetrachloride and chloroform. Show how this result explains the use of distillation as a separation method.

A solution of 49.0% \(H_2 SO_4\) by mass has a density of \(1.39 \ g/cm^3\) at 293 K. A \(25.0 \ cm^3\) sample of this solution is mixed with enough water to increase the volume of the solution to \(99.8 \ cm^3\). Find the molarity of sulfuric acid in this solution.

Find the mass of urea (CH4N2O) needed to prepare 50.0 g of a solution in water in which the mole fraction of urea is 0.0770.

A solution contains 10.05 g of unknown compound dissolved in 50.0 mL of water. (Assume a density of 1.00 g/mL for water.) The freezing point of the solution is -3.16 oC. The mass percent composition of the compound is 60.97% C, 11.94% H, and the rest is O. What is the molecular formula of the compound?

The osmotic pressure of a solution containing \(2.10 \mathrm{~g}\) of an unknown compound dissolved in \(175.0 \mathrm{~mL}\) of solution at \(25^{\circ} \mathrm{C}\) is \(1.93 \mathrm{~atm}\). The combustion of \(24.02 \mathrm{~g}\) of the unknown compound produced \(28.16 \mathrm{~g} \mathrm{CO}_2\) and \(8.64 \mathrm{~g} \mathrm{H}_2 \mathrm{O}\). What is the molecular formula of the compound (which contains only carbon, hydrogen, and oxygen)?

d A 100.0 mL aqueous sodium chloride solution is 13.5% NaCl by mass and has a density of 1.12 g/mL. What would you add (solute or solvent) and what mass of it to make the boiling point of the solution 104.4 °C? (Use i = 1.8 for NaCl.)

A 50.0 mL solution is initially 1.55% MgCl2 by mass and has a density of 1.05 g/mL. What is the freezing point of the solution after you add an additional 1.35 g MgCl2? (Use i = 2.5 for MgCl2.)

The small bubbles that form on the bottom of a water pot that is being heated (before boiling) are due to dissolved air coming out of solution. Use Henry’s law and the solubilities given to calculate the total volume of nitrogen and oxygen gas that should bubble out of 1.5 L of water upon warming from 25 oC to 50 oC. Assume that the water is initially saturated with nitrogen and oxygen gas at 25 oC and a total pressure of 1.0 atm. Assume that the gas bubbles out at a temperature of 50 oC. The solubility of oxygen gas at 50 oC is 27.8 mg/L at an oxygen pressure of 1.00 atm. The solubility of nitrogen gas at 50 oC is 14.6 mg/L at a nitrogen pressure of 1.00 atm. Assume that the air above the water contains an oxygen partial pressure of 0.21 atm and a nitrogen partial pressure of 0.78 atm.

Problem 126E The vapor above a mixture of pentane and hexane at room temperature contains 35.5% pentane by mass. What is the mass percent composition of the solution? Pure pentane and hexane have vapor pressures of 425 torr and 151 torr, respectively, at room temperature.

A 1.10 g sample contains only glucose (C6H12O6) and sucrose (C12H22O11). When the sample is dissolved in water to a total solution volume of 25.0 mL, the osmotic pressure of the solution is 3.78 atm at 298 K. What is the mass percent composition of glucose and sucrose in the sample?

Problem 128E A solution is prepared by mixing 631 mL of methanol with 501 mL of water. The molarity of methanol in the resulting solution is 14.29 M. The density of methanol at this temperature is 0.792 g/mL. Calculate the difference in volume between this solution and the total volume of water and methanol that were mixed to prepare the solution.

Two alcohols, isopropyl alcohol and propyl alcohol, have the same molecular formula, C3H8O. A solution of the two that is two-thirds by mass isopropyl alcohol has a vapor pressure of 0.110 atm at 313 K. A solution that is one-third by mass isopropyl alcohol has a vapor pressure of 0.089 atm at 313 K. Calculate the vapor pressure of each pure alcohol at this temperature. Explain the difference given that the formula of propyl alcohol is CH3CH2CH2OH and that of isopropyl alcohol is (CH3)2CHOH.

A metal, M, of atomic mass 96 amu reacts with fluorine to form a salt that can be represented as MFx. In order to determine x and therefore the formula of the salt, a boiling point elevation experiment is performed. A 9.18 g sample of the salt is dissolved in 100.0 g of water and the boiling point of the solution is found to be 374.38 K. Find the formula of the salt. (Assume complete dissociation of the salt in solution.)

Sulfuric acid in water dissociates completely into H+ and HSO4- ions. The HSO4- ion dissociates to a limited extent into H+ and SO42-. The freezing point of a 0.1000 m solution of sulfuric acid in water is 272.76 K. Calculate the molality of SO42- in the solution, assuming ideal solution behavior.

A solution of 75.0 g of benzene ( C6H6 ) and 75.0 g of toluene ( C7H8 ) has a total vapor pressure of 80.9 mmHg at 303 K. Another solution of 100.0 g benzene and 50.0 g toluene has a total vapor pressure of 93.9 mmHg at this temperature. Find the vapor pressure of pure benzene and pure toluene at 303 K.

A solution is prepared by dissolving 11.60 g of a mixture of sodium carbonate and sodium bicarbonate in 1.00 L of water. A 300.0 cm3 sample of the solution is treated with excess HNO3 and boiled to remove all the dissolved gas. A total of 0.940 L of dry CO2 is collected at 298 K and 0.972 atm. Find the molarity of the carbonate and bicarbonate in the solution.

Substance A is a nonpolar liquid and has only dispersion forces among its constituent particles. Substance B is also a nonpolar liquid and has about the same magnitude of dispersion forces among its constituent particles as substance A. When substance A and B are combined, they spontaneously mix. a. Why do the two substances mix? b. Predict the sign and magnitude of soln. c. Determine the signs and relative magnitudes of solute, solvent, and mix.

Problem 135E A power plant built on a river uses river water as a coolant. The water is warmed as it is used in heat exchangers within the plant. Should the warm water be immediately cycled back into the river? Why or why not?

If each substance listed here costs the same amount per kilogram, which would be most cost-effective as a way to lower the freezing point of water? (Assume complete dissociation for all ionic compounds.) Explain. a. HOCH2CH2OH b. NaCl c. KCl d. MgCl2 e. SrCl2

The vapor pressure of a 1 M ionic solution is different from the vapor pressure of a 1 M nonelectrolyte solution. In both cases, the solute is nonvolatile. Which set of diagrams best represents the differences between the two solutions and their vapors?

Problem 138E A helium balloon inflated on one day will fall to the ground by the next day. The volume of the balloon decreases somewhat overnight but not by enough to explain why it no longer floats. (If you inflate a new balloon with helium to the same size as the balloon that fell to the ground, the newly inflated balloon floats.) Explain.

Why does Rachel Carson begin with There was once a town . . . , as though she were writing a fairy tale? Is this a fairy tale of sorts? How does Carson present the town in paragraphs 1 and 2?

Carson claims in paragraph 12 that [t]he most alarming of . . . assaults upon the environment is the contamination of air, earth, rivers, and sea with dangerous and even lethal materials. Is contamination still the most alarming assault on the environment, or has another problem taken its place? Explain your response.

In paragraph 16, Carson claims that humankind is engaged in a war against nature and describes the targets of that war. Do you agree that targeting certain things for destruction (or at least control) means we are at war with nature? Can we be at war with something that is not our intended target? Explain.

Carson says the products used to kill bugs should be called biocides instead of insecticides (para. 17). Why? What is the difference?

What has changed since Carson wrote Silent Spring? Has the natural environment improved? Has it declined? Since Carsons time, have we become more concerned with the effect we have on nature or less concerned? Explain your response

What does Jean Rostand mean by our obligation to endure (para. 36)? How is our right to know related to this obligation?

Carson says that the public is fed little tranquilizing pills of half truth when it contests the use of pesticides (para. 36). Why is this metaphor effective?

What do you think Carsons purpose was in ending the final paragraph (and the chapter) with someone elses words?

Expressing a view widely held in 1949, Leopold writes of the discontent that labels itself organic farming (para. 40). Do we still see organic farming as a discontent today? Explain.

At the beginning of The Outlook, Leopold characterizes the modern (para. 44). Does that characterization hold true today? Explain your response.

How does Leopolds use of the key- log metaphor (para. 48) move his essay toward its conclusion?

Leopold wrote The Land Ethic over sixty years ago. To what extent do his ideas apply to our current environmental situation?

In the following paragraph from The End of Nature by Bill McKibben, the cumulative sentences are in blue. Rewrite them as periodic sentences. How does the sentence structure affect the focus, tone, and meaning of each of the three sentences? Discuss the rhetorical effectiveness of the way that McKibben decided to write them.

The following paragraph from The Future of Life by E. O. Wilson consists of three sentences: a simple declarative sentence, then a periodic sentence, and finally a cumulative sentence. Keep the first one as it is; then rewrite the periodic sentence as cumulative and the cumulative as periodic. Compare the two paragraphs. Discuss the relationship among the sentences in each paragraph and the rhetorical effect of syntax on meaning and tone.

When I started trying to follow the industrial food chain the one that now feeds most of us most of the time and typically culminates either in a supermarket or fast- food meal I expected that my investigations would lead me to a wide variety of places. Michael Pollan, para. 8

Hidden from immediate view in the butterfly- bright meadow, in the dusky thicket, in the oak and holly wood, are the surveyors stakes, for someone wants to build a mall exactly there some gas stations and supermarkets, some pizza and video shops, a health club, maybe a bulimia treatment center. Joy Williams, para. 1

The following selection is from paragraph 11 of A Naturalist in the Supermarket by Michael Pollan. Read the paragraph carefully, and identify whether the underlined sentences are cumulative or periodic. Discuss the effect of the syntax in each case. Then, imitating the structure of each, write a sentence of your own on an environmental issue.

ExxonMobil, self- described as the worlds largest publicly traded international oil and gas company, providing energy that helps underpin growing economies and improve living standards around the world, makes the following statements on its Web site: Managing long- term climate risks Rising greenhouse- gas emissions pose significant risks to society and ecosystems. Since most of these emissions are energy- related, any integrated approach to meeting the worlds growing energy needs over the coming decades must incorporate strategies to address the risk of climate change. Managing climate change risks Our strategy to reduce greenhouse-gas emissions is focused on increasing energy efficiency in the short term, implementing proven emission- reducing technologies in the near and medium term, and developing breakthrough, game- changing technologies for the long term. Technological innovation will play a central role in our ability to increase supply, improve efficiency, and reduce emissions. Approximately 90 percent of the greenhouse-gas emissions generated by petroleum products are released when customers use our products, and the remaining 10 percent are generated by industry operations. Therefore, technology is also needed to reduce energy- related emissions by end users. In a time when we still hear many people even some public officials questioning the reality of climate change and global warming, it might seem surprising to discover the perspective above coming from a large energy company. What do these statements suggest about climate change? About global warming? About the relationship between economic concerns and environmental protection? Finally, what do they suggest about the essential question posed at the beginning of this chapter: What is our responsibility to the natural environment? Refer to several texts from this chapter as you answer these questions.

What are the common units for expressing solution concentration?

How are parts by mass and parts by volume used in calculations?

What is the effect of a nonvolatile solute on the vapor pressure of a liquid? Why is the vapor pressure of a solution different from the vapor pressure of the pure liquid solvent?

What is Raoults law? For what kind of calculations is Raoults law useful?

Explain the difference between an ideal and a nonideal solution.

What is the effect on vapor pressure of a solution with particularly strong solutesolvent interactions? With particularly weak solutesolvent interactions?

Explain why the lower vapor pressure for a solution containing a nonvolatile solute results in a higher boiling point and lower melting point compared to the pure solvent.

What are colligative properties?

What is osmosis? What is osmotic pressure?

Explain the meaning of the vant Hoff factor and its role in determining the colligative properties of solutions containing ionic solutes.

Describe a colloidal dispersion. What is the difference between a colloidal dispersion and a true solution?

What is the Tyndall effect and how can it be used to help identify colloidal dispersions?

What is the Tyndall effect and how can it be used to help identify colloidal dispersions?

Pick an appropriate solvent from Table 12.3 to dissolve each substance. State the kind of intermolecular forces that would occur between the solute and solvent in each case. a. motor oil (nonpolar) b. ethanol (polar, contains an OH group) c. lard (nonpolar) d. potassium chloride (ionic)

Pick an appropriate solvent from Table 12.3 to dissolve each substance. State the kind of intermolecular forces that would occur between the solute and solvent in each case. a. isopropyl alcohol (polar, contains an OH group) b. sodium chloride (ionic) c. vegetable oil (nonpolar) d. sodium nitrate (ionic)

Which molecule would you expect to be more soluble in water, CH3CH2CH2OH or HOCH2CH2CH2OH?

Which molecule would you expect to be more soluble in water, CCl4 or CH2Cl2?

For each compound, would you expect greater solubility in water or in hexane? Indicate the kinds of intermolecular forces that occur between the solute and the solvent in which the molecule is most soluble. a. glucose b. naphthalene c. dimethyl ether d. alanine (an amino acid)

For each compound, would you expect greater solubility in water or in hexane? Indicate the kinds of intermolecular forces that would occur between the solute and the solvent in which the molecule is most soluble. a. toluene b. sucrose (table sugar) c. isobutene d. ethylene glycol

When ammonium chloride 1NH4Cl2 is dissolved in water, the solution becomes colder. a. Is the dissolution of ammonium chloride endothermic or exothermic? b. What can you conclude about the relative magnitudes of the lattice energy of ammonium chloride and its heat of hydration? c. Sketch a qualitative energy diagram similar to Figure 12.7 for the dissolution of NH4Cl. d. Why does the solution form? What drives the process?

When lithium iodide (LiI) is dissolved in water, the solution becomes hotter. a. Is the dissolution of lithium iodide endothermic or exothermic? b. What can you conclude about the relative magnitudes of the lattice energy of lithium iodide and its heat of hydration? c. Sketch a qualitative energy diagram similar to Figure 12.7 for the dissolution of LiI. d. Why does the solution form? What drives the process?

Silver nitrate has a lattice energy of -820 kJ>mol and a heat of solution of -22.6 kJ>mol . Calculate the heat of hydration for silver nitrate.

Use the data to calculate the heats of hydration of lithium chloride and sodium chloride. Which of the two cations, lithium or sodium, has stronger iondipole interactions with water? Why?

Lithium iodide has a lattice energy of -7.3 * 102 kJ>mol and a heat of hydration of -793 kJ>mol. Find the heat of solution for lithium iodide and determine how much heat is evolved or absorbed when 15.0 g of lithium iodide completely dissolves in water.

Potassium nitrate has a lattice energy of -163.8 kcal>mol and a heat of hydration of -155.5 kcal>mol. How much potassium nitrate has to dissolve in water to absorb 1.00 * 102 kJ of heat?

A solution contains 25 g of NaCl per 100.0 g of water at 25 C. Is the solution unsaturated, saturated, or supersaturated? ( Use Figure 12.11 .)

A solution contains 32 g of \(KNO_3\) per 100.0 g of water at \(25 \ ^\circ C\). Is the solution unsaturated, saturated, or supersaturated? (Use Figure 12.11.)

A KNO3 solution containing 45 g of KNO3 per 100.0 g of water is cooled from 40 C to 0 C. What happens during cooling? ( Use Figure 12.11 .)

A KCl solution containing 42 g of KCl per 100.0 g of water is cooled from 60 C to 0 C. What happens during cooling? ( Use Figure 12.11 .) 4

Some laboratory procedures involving oxygen-sensitive reactants or products call for using water that has been boiled (and then cooled). Explain.

A person preparing a fish tank fills the tank with water that has been boiled (and then cooled). When the person puts fish into the tank, they die. Explain.

Scuba divers breathing air at increased pressure can suffer from nitrogen narcosis-a condition resembling drunkenness-when the partial pressure of nitrogen exceeds about \(4 \mathrm{~atm}\). What property of gas/water solutions causes this to happen? How can a diver reverse this effect?

Scuba divers breathing air at increased pressure can suffer from oxygen toxicitytoo much oxygen in their bloodstream when the partial pressure of oxygen exceeds about 1.4 atm. What happens to the amount of oxygen in a divers bloodstream when he or she breathes oxygen at elevated pressures? How can this be reversed?

Calculate the mass of nitrogen dissolved at room temperature in an 80.0 L home aquarium. Assume a total pressure of 1.0 atm and a mole fraction for nitrogen of 0.78.

Use Henrys law to determine the molar solubility of helium at a pressure of 1.0 atm and 25 C.

An aqueous NaCl solution is made using 112 g of NaCl diluted to a total solution volume of 1.00 L. Calculate the molarity, molality, and mass percent of the solution. (Assume a density of 1.08 g>mL for the solution.)

An aqueous KNO3 solution is made using 72.5 g of KNO3 diluted to a total solution volume of 2.00 L. Calculate the molarity, molality, and mass percent of the solution. (Assume a density of 1.05 g>mL for the solution.)

To what volume should you dilute 50.0 mL of a 5.00 M KI solution so that 25.0 mL of the diluted solution contains 3.05 g of KI?

To what volume should you dilute 125 mL of an 8.00 M CuCl2 solution so that 50.0 mL of the diluted solution contains 4.67 g CuCl2?

Silver nitrate solutions are often used to plate silver onto other metals. What is the maximum amount of silver (in grams) that can be plated out of 4.8 L of an AgNO3 solution containing 3.4% Ag by mass? Assume that the density of the solution is 1.01 g>mL.

A dioxin-contaminated water source contains 0.085% dioxin by mass. How much dioxin is present in 2.5 L of this water? Assume a density of 1.00 g>mL.

A hard water sample contains 0.0085% Ca by mass (in the form of Ca2+ ions). How much water (in grams) contains 1.2 g of Ca? (1.2 g of Ca is the recommended daily allowance of calcium for those between 19 and 24 years old.)

Lead is a toxic metal that affects the central nervous system. A Pb-contaminated water sample contains 0.0011% Pb by mass. How much of the water (in mL) contains 150 mg of Pb? (Assume a density of 1.0 g/mL.)

You can purchase nitric acid in a concentrated form that is 70.3% HNO3 by mass and has a density of 1.41 g>mL . Describe exactly how you would prepare 1.15 L of 0.100 M HNO3 from the concentrated solution.

You can purchase hydrochloric acid in a concentrated form that is 37.0% HCl by mass and that has a density of 1.20 g>mL. Describe exactly how to prepare 2.85 L of 0.500 M HCl from the concentrated solution.

Describe how to prepare each solution from the dry solute and the solvent. a. 1.00 * 102 mL of 0.500 M KCl b. 1.00 * 102 g of 0.500 m KCl c. 1.00 * 102 g of 5.0% KCl solution by mass

Describe how to prepare each solution from the dry solute and the solvent. a. 125 mL of 0.100 M NaNO3 b. 125 g of 0.100 m NaNO3 c. 125 g of 1.0% NaNO3 solution by mass

A solution is prepared by dissolving 28.4 g of glucose 1C6H12O62 in 355 g of water. The final volume of the solution is 378 mL. For this solution, calculate the concentration in each unit. a. molarity b. molality c. percent by mass d. mole fraction e. mole percent

A solution is prepared by dissolving 20.2 mL of methanol 1CH3OH2 in 100.0 mL of water at 25 C. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g>mL and 1.00 g>mL, respectively. For this solution, calculate the concentration in each unit. a. molarity b. molality c. percent by mass d. mole fraction e. mole percent

Household hydrogen peroxide is an aqueous solution containing 3.0% hydrogen peroxide by mass. What is the molarity of this solution? (Assume a density of 1.01 g>mL.)

One brand of laundry bleach is an aqueous solution containing 4.55% sodium hypochlorite (NaOCl) by mass. What is the molarity of this solution? (Assume a density of 1.02 g>mL.)

An aqueous solution contains 36% HCl by mass. Calculate the molality and mole fraction of the solution.

An aqueous solution contains 5.0% NaCl by mass. Calculate the molality and mole fraction of the solution.

A beaker contains 100.0 mL of pure water. A second beaker contains 100.0 mL of seawater. The two beakers are left side by side on a lab bench for 1 week. At the end of the week, the liquid level in both beakers has decreased. However, the level has decreased more in one of the beakers than in the other. Which one and why?

Which solution has the highest vapor pressure? a. 20.0 g of glucose 1C6H12O62 in 100.0 mL of water b. 20.0 g of sucrose 1C12H22O112 in 100.0 mL of water c. 10.0 g of potassium acetate KC2H3O2 in 100.0 mL of water

Calculate the vapor pressure of a solution containing 24.5 g of glycerin 1C3H8O32 in 135 mL of water at 30.0 C. The vapor pressure of pure water at this temperature is 31.8 torr. Assume that glycerin is not volatile and dissolves molecularly (i.e., it is not ionic), and use a density of 1.00 g>mL for the water.

A solution contains naphthalene 1C10H82 dissolved in hexane 1C6H142 at a concentration of 12.35% naphthalene by mass. Calculate the vapor pressure at 25 C of hexane above the solution. The vapor pressure of pure hexane at 25 C is 151 torr. 7

A solution contains naphthalene 1C10H82 dissolved in hexane 1C6H142 at a concentration of 12.35% naphthalene by mass. Calculate the vapor pressure at 25 C of hexane above the solution. The vapor pressure of pure hexane at 25 C is 151 torr. 7

A solution contains a mixture of pentane and hexane at room temperature. The solution has a vapor pressure of 258 torr. Pure pentane and hexane have vapor pressures of 425 torr and 151 torr, respectively, at room temperature. What is the mole fraction composition of the mixture? (Assume ideal behavior.)

A solution contains 4.08 g of chloroform 1CHCl32 and 9.29 g of acetone 1CH3COCH32. The vapor pressures at 35 C of pure chloroform and pure acetone are 295 torr and 332 torr, respectively. Assuming ideal behavior, calculate the vapor pressures of each of the components and the total vapor pressure above the solution. The experimentally measured total vapor pressure of the solution at 35 C was 312 torr. Is the solution ideal? If not, what can you say about the relative strength of chloroformacetone interactions compared to the acetoneacetone and chloroformchloroform interactions?

A solution of methanol and water has a mole fraction of water of 0.312 and a total vapor pressure of 211 torr at 39.9 C. The vapor pressures of pure methanol and pure water at this temperature are 256 torr and 55.3 torr, respectively. Is the solution ideal? If not, what can you say about the relative strengths of the solutesolvent interactions compared to the solutesolute and solventsolvent interactions?

A glucose solution contains 55.8 g of glucose 1C6H12O62 in 455 g of water. Determine the freezing point and boiling point of the solution.

An ethylene glycol solution contains 21.2 g of ethylene glycol 1C2H6O22 in 85.4 mL of water. Determine the freezing point and boiling point of the solution. (Assume a density of 1.00 g>mL for water.)

Calculate the freezing point and melting point of a solution containing 10.0 g of naphthalene (C 10 H 8 ) in 100.0 mL of benzene. Benzene has a density of 0.877 g>cm 3 .

Calculate the freezing point and melting point of a solution containing 7.55 g of ethylene glycol (C 2 H 6 O 2 ) in 85.7 mL of ethanol. Ethanol has a density of 0.789 g>cm 3

An aqueous solution containing 17.5 g of an unknown molecular (nonelectrolyte) compound in 100.0 g of water has a freezing point of -1.8 C. Calculate the molar mass of the unknown compound.

An aqueous solution containing 35.9 g of an unknown molecular (nonelectrolyte) compound in 150.0 g of water has a freezing point of -1.3 C. Calculate the molar mass of the unknown compound.

Calculate the osmotic pressure of a solution containing 24.6 g of glycerin 1C3H8O32 in 250.0 mL of solution at 298 K.

What mass of sucrose 1C12H22O112 would you combine with 5.00 * 102 g of water to make a solution with an osmotic pressure of 8.55 atm at 298 K? (Assume a density of 1.0 g>mL for the solution.)

A solution containing 27.55 mg of an unknown protein per 25.0 mL solution was found to have an osmotic pressure of 3.22 torr at 25 C. What is the molar mass of the protein? 8

Calculate the osmotic pressure of a solution containing 18.75 mg of hemoglobin in 15.0 mL of solution at 25 C. The molar mass of hemoglobin is 6.5 * 104 g>mol.

Calculate the freezing point and boiling point of each aqueous solution, assuming complete dissociation of the solute. a. 0.100 m K2S b. 21.5 g of CuCl2 in 4.50 * 102 g water c. 5.5% NaNO3 by mass (in water)

Calculate the freezing point and boiling point in each solution, assuming complete dissociation of the solute. a. 10.5 g FeCl3 in 1.50 * 102 g water b. 3.5% KCl by mass (in water) c. 0.150 m MgF2

What mass of salt (NaCl) should you add to 1.00 L of water in an ice cream maker to make a solution that freezes at -10.0 C? Assume complete dissociation of the NaCl and density of 1.00 g>mL for water.

Determine the required concentration (in percent by mass) for an aqueous ethylene glycol (C 2 H 6 O 2 ) solution to have a boiling point of 104.0 C.

Use the vant Hoff factors in Table 12.9 to calculate each colligative property: a. the melting point of a 0.100 m iron(III) chloride solution b. the osmotic pressure of a 0.085 M potassium sulfate solution at 298 K c. the boiling point of a 1.22% by mass magnesium chloride solution

Assuming the van’t Hoff factors in Table 12.9, calculate the mass of solute required to make each aqueous solution: a. a sodium chloride solution containing \(1.50 \times 10^{2} \mathrm{\ g}\) of water that has a melting point of \(-1.0\ ^{\circ}\mathrm{C}\) b. \(2.50 \times 10^{2} \mathrm{\ mL}\) of a magnesium sulfate solution that has an osmotic pressure of 3.82 atm at 298 K c. an iron(III) chloride solution containing \(2.50 \times 10^{2} \mathrm{\ g}\) of water that has a boiling point of \(102\ ^{\circ}\mathrm{C}\)

A 1.2 m aqueous solution of an ionic compound with the formula MX 2 has a boiling point of 101.4 C. Calculate the vant Hoff factor ( i ) for MX 2 at this concentration.

A \(0.95 \mathrm{~m}\) aqueous solution of an ionic compound with the formula MX has a freezing point of \(-3.0^{\circ} \mathrm{C}\). Calculate the van't Hoff factor ( i ) for MX at this concentration.

A 0.100 M ionic solution has an osmotic pressure of 8.3 atm at 25 C. Calculate the vant Hoff factor ( i ) for this solution.

A solution contains 8.92 g of KBr in 500.0 mL of solution and has an osmotic pressure of 6.97 atm at \(25\ ^{\circ}\mathrm{C}\). Calculate the van't Hoff factor (i) for KBr at this concentration.

Calculate the vapor pressure at 25 C of an aqueous solution that is 5.50% NaCl by mass. (Assume complete dissociation of the solute.)

Calculate the vapor pressure at 25 C of an aqueous solution that is 5.50% NaCl by mass. (Assume complete dissociation of the solute.)

The solubility of carbon tetrachloride 1CCl42 in water at 25 C is 1.2 g>L. The solubility of chloroform 1CHCl32 at the same temperature is 10.1 g>L. Why is chloroform almost ten times more soluble in water than carbon tetrachloride?

The solubility of phenol in water at 25 C is 8.7 g>L. The solubility of naphthol at the same temperature is only 0.074 g>L. Examine the structures of phenol and naphthol shown here and explain why phenol is so much more soluble than naphthol.

Potassium perchlorate 1KClO42 has a lattice energy of -599 kJ>mol and a heat of hydration of -548 kJ>mol. Find the heat of solution for potassium perchlorate and determine the temperature change that occurs when 10.0 g of potassium perchlorate is dissolved with enough water to make 100.0 mL of solution. (Assume a heat capacity of 4.05 J>g # C for the solution and a density of 1.05 g>mL.)

Sodium hydroxide (NaOH) has a lattice energy of -887 kJ>mol and a heat of hydration of -932 kJ>mol . How much solution could be heated to boiling by the heat evolved by the dissolution of 25.0 g of NaOH? (For the solution, assume a heat capacity of 4.0 J>g # C, an initial temperature of 25.0 C, a boiling point of 100.0 C, and a density of 1.05 g>mL.) 10

A saturated solution forms when 0.0537 L of argon, at a pressure of 1.0 atm and temperature of 25 C, is dissolved in 1.0 L of water. Calculate the Henrys law constant for argon.

A gas has a Henry's law constant of 0.112 M/atm. What total volume of solution is needed to completely dissolve 1.65 L of the gas at a pressure of 725 torr and a temperature of \(25\ ^{\circ}\mathrm{C}\)?

The Safe Drinking Water Act (SDWA) sets a limit for mercurya toxin to the central nervous systemat 0.0020 ppm by mass. Water suppliers must periodically test their water to ensure that mercury levels do not exceed this limit. Suppose water becomes contaminated with mercury at twice the legal limit (0.0040 ppm). How much of this water would a person have to consume to ingest 50.0 mg of mercury?

Water softeners often replace calcium ions in hard water with sodium ions. Since sodium compounds are soluble, the presence of sodium ions in water does not cause the white, scaly residues caused by calcium ions. However, calcium is more beneficial to human health than sodium because calcium is a necessary part of the human diet, while high levels of sodium intake are linked to increases in blood pressure. The U.S. Food and Drug Administration (FDA) recommends that adults ingest less than 2.4 g of sodium per day. How many liters of softened water, containing a sodium concentration of 0.050% sodium by mass, would a person have to consume to exceed the FDA recommendation? (Assume a water density of 1.0 g>mL.)

An aqueous solution contains 12.5% NaCl by mass. What mass of water (in grams) is contained in 2.5 L of the vapor above this solution at 55 C? The vapor pressure of pure water at 55 C is 118 torr. (Assume complete dissociation of NaCl.)

The vapor above an aqueous solution contains 19.5 mg water per liter at 25 C. Assuming ideal behavior, what is the concentration of the solute within the solution in mole percent?

. What is the freezing point of an aqueous solution that boils at 106.5 C?

What is the boiling point of an aqueous solution that has a vapor pressure of 20.5 torr at 25 C? (Assume a nonvolatile solute.)

An isotonic solution contains 0.90% NaCl mass to volume. Calculate the percent mass to volume for isotonic solutions containing each solute at 25 C. Assume a vant Hoff factor of 1.9 for all ionic solutes. a. KCl b. NaBr c. glucose 1C6H12O62

Magnesium citrate, Mg3 1C6H5O722 belongs to a class of laxatives called hyperosmotics , which cause rapid emptying of the bowel. When a concentrated solution of magnesium citrate is consumed, it passes through the intestines, drawing water and promoting diarrhea, usually within 6 hours. Calculate the osmotic pressure of a magnesium citrate laxative solution containing 28.5 g of magnesium citrate in 235 mL of solution at 37 C (approximate body temperature). Assume complete dissociation of the ionic compound.

A solution is prepared from 4.5701 g of magnesium chloride and 43.238 g of water. The vapor pressure of water above this solution is 0.3624 atm at 348.0 K. The vapor pressure of pure water at this temperature is 0.3804 atm. Find the value of the vant Hoff factor ( i) for magnesium chloride in this solution.

When HNO2 is dissolved in water it partially dissociates according to the equation HNO2 N H - + NO2 -. A solution is prepared that contains 7.050 g of HNO2 in 1.000 kg of water. Its freezing point is 20.2929 C. Calculate the fraction of HNO2 that has dissociated.

A solution of a nonvolatile solute in water has a boiling point of 375.3 K. Calculate the vapor pressure of water above this solution at 338 K. The vapor pressure of pure water at this temperature is 0.2467 atm.

The density of a 0.438 M solution of potassium chromate 1K2CrO42 at 298 K is 1.063 g>mL. Calculate the vapor pressure of water above the solution. The vapor pressure of pure water at this temperature is 0.0313 atm. (Assume complete dissociation of the solute.)

The density of a 0.438 M solution of potassium chromate 1K2CrO42 at 298 K is 1.063 g>mL. Calculate the vapor pressure of water above the solution. The vapor pressure of pure water at this temperature is 0.0313 atm. (Assume complete dissociation of the solute.)

Distillation is a method of purification based on successive separations and recondensations of vapor above a solution. Use the result of the previous problem to calculate the mole fraction of chloroform in the vapor above a solution obtained by three successive separations and condensations of the vapors above the original solution of carbon tetrachloride and chloroform. Show how this result explains the use of distillation as a separation method.

A solution of 49.0% H 2 SO 4 by mass has a density of 1.39 g>cm3 at 293 K. A 25.0 cm3 sample of this solution is mixed with enough water to increase the volume of the solution to 99.8 cm3 . Find the molarity of sulfuric acid in this solution.

Find the mass of urea ( CH4N2O ) needed to prepare 50.0 g of a solution in water in which the mole fraction of urea is 0.0770.

A solution contains 10.05 g of unknown compound dissolved in 50.0 mL of water. (Assume a density of 1.00 g>mL for water.) The freezing point of the solution is -3.16 C . The mass percent composition of the compound is 60.97% C, 11.94% H, and the rest is O. What is the molecular formula of the compound?

The osmotic pressure of a solution containing 2.10 g of an unknown compound dissolved in 175.0 mL of solution at 25 C is 1.93 atm. The combustion of 24.02 g of the unknown compound produced 28.16 g CO 2 and 8.64 g H 2 O. What is the molecular formula of the compound (which contains only carbon, hydrogen, and oxygen)?

A 100.0 mL aqueous sodium chloride solution is 13.5% NaCl by mass and has a density of 1.12 g>mL. What would you add (solute or solvent) and what mass of it to make the boiling point of the solution 104.4 C? (Use i = 1.8 for NaCl.)

A 50.0 mL solution is initially 1.55% MgCl2 by mass and has a density of 1.05 g>mL. What is the freezing point of the solution after you add an additional 1.35 g MgCl2 ? (Use i = 2.5 for MgCl2. )

The small bubbles that form on the bottom of a water pot that is being heated (before boiling) are due to dissolved air coming out of solution. Use Henry's law and the solubilities given to calculate the total volume of nitrogen and oxygen gas that should bubble out of 1.5 L of water upon warming from \(25\ ^{\circ}\mathrm{C}\) to \(50\ ^{\circ}\mathrm{C}\). Assume that the water is initially saturated with nitrogen and oxygen gas at \(25\ ^{\circ}\mathrm{C}\) and a total pressure of 1.0 atm. Assume that the gas bubbles out at a temperature of \(50\ ^{\circ}\mathrm{C}\). The solubility of oxygen gas at \(50\ ^{\circ}\mathrm{C}\) is 27.8 mg/L at an oxygen pressure of 1.00 atm. The solubility of nitrogen gas at \(50\ ^{\circ}\mathrm{C}\) is 14.6 mg/L at a nitrogen pressure of 1.00 atm. Assume that the air above the water contains an oxygen partial pressure of 0.21 atm and a nitrogen partial pressure of 0.78 atm.

The vapor above a mixture of pentane and hexane at room temperature contains 35.5% pentane by mass. What is the mass percent composition of the solution? Pure pentane and hexane have vapor pressures of 425 torr and 151 torr, respectively, at room temperature.

A 1.10 g sample contains only glucose 1C6H12O62 and sucrose 1C12H22O112. When the sample is dissolved in water to a total solution volume of 25.0 mL, the osmotic pressure of the solution is 3.78 atm at 298 K. What is the mass percent composition of glucose and sucrose in the sample?

A solution is prepared by mixing 631 mL of methanol with 501 mL of water. The molarity of methanol in the resulting solution is 14.29 M. The density of methanol at this temperature is 0.792 g>mL. Calculate the difference in volume between this solution and the total volume of water and methanol that were mixed to prepare the solution.

Two alcohols, isopropyl alcohol and propyl alcohol, have the same molecular formula, C3H8O. A solution of the two that is two-thirds by mass isopropyl alcohol has a vapor pressure of 0.110 atm at 313 K. A solution that is one-third by mass isopropyl alcohol has a vapor pressure of 0.089 atm at 313 K. Calculate the vapor pressure of each pure alcohol at this temperature. Explain the difference given that the formula of propyl alcohol is CH3CH2CH2OH and that of isopropyl alcohol is 1CH322CHOH.

A metal, M, of atomic mass 96 amu reacts with fluorine to form a salt that can be represented as MFx. In order to determine x and therefore the formula of the salt, a boiling point elevation experiment is performed. A 9.18 g sample of the salt is dissolved in 100.0 g of water and the boiling point of the solution is found to be 374.38 K. Find the formula of the salt. (Assume complete dissociation of the salt in solution.)

Sulfuric acid in water dissociates completely into H+ and HSO4 - ions. The HSO4 - ion dissociates to a limited extent into H+ and SO4 2- . The freezing point of a 0.1000 m solution of sulfuric acid in water is 272.76 K. Calculate the molality of SO4 2- in the solution, assuming ideal solution behavior.

A solution of 75.0 g of benzene ( C6H6 ) and 75.0 g of toluene ( C7H8 ) has a total vapor pressure of 80.9 mmHg at 303 K. Another solution of 100.0 g benzene and 50.0 g toluene has a total vapor pressure of 93.9 mmHg at this temperature. Find the vapor pressure of pure benzene and pure toluene at 303 K.

A solution of 75.0 g of benzene ( C6H6 ) and 75.0 g of toluene ( C7H8 ) has a total vapor pressure of 80.9 mmHg at 303 K. Another solution of 100.0 g benzene and 50.0 g toluene has a total vapor pressure of 93.9 mmHg at this temperature. Find the vapor pressure of pure benzene and pure toluene at 303 K.

Substance A is a nonpolar liquid and has only dispersion forces among its constituent particles. Substance B is also a nonpolar liquid and has about the same magnitude of dispersion forces among its constituent particles as substance A. When substance A and B are combined, they spontaneously mix. a. Why do the two substances mix? b. Predict the sign and magnitude of Hsoln. c. Determine the signs and relative magnitudes of Hsolute, Hsolvent, and Hmix. 135

A power plant built on a river uses river water as a coolant. The water is warmed as it is used in heat exchangers within the plant. Should the warm water be immediately cycled back into the river? Why or why not?

The vapor pressure of a 1 M ionic solution is different from the vapor pressure of a 1 M nonelectrolyte solution. In both cases, the solute is nonvolatile. Which set of diagrams best represents the differences between the two solutions and their vapors?

If each substance listed here costs the same amount per kilogram, which would be most cost-effective as a way to lower the freezing point of water? (Assume complete dissociation for all ionic compounds.) Explain. a. HOCH2CH2OH b. NaCl c. KCl d. MgCl2 e. SrCl2

If each substance listed here costs the same amount per kilogram, which would be most cost-effective as a way to lower the freezing point of water? (Assume complete dissociation for all ionic compounds.) Explain. a. HOCH2CH2OH b. NaCl c. KCl d. MgCl2 e. SrCl2