A mixture of NaCl and sucrose (C12H22O12) of combined mass

Problem 1QP Distinguish between an unsaturated solution, a saturated solution, and a supersaturated solution.

Problem 2QP Describe the different types of solutions that can be formed by the combination of solids, liquids, and gases. Give examples of each type of solution.

Problem 149AP A mixture of two volatile liquids is said to be ideal if each component obeys Raoult’s law: Two volatile liquids A (molar mass 100 g/mol) and B (molar mass 110 g/mol) form an ideal solution. At 55°C, A has a vapor pressure of 98 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 55°C. (c) Suppose that some of the vapor over the solution at 55°C is condensed to a liquid. Calculate the mole fraction of each component in the condensed liquid, (d) Calculate the partial pressures of the components above the condensed liquid at 55°C.

Problem 7QP Explain why dissolving a solid almost always leads to an increase in disorder.

Problem 3QP Briefly describe the solution process at the molecular level. Use the dissolution of a solid in a liquid as an example.

Problem 4QP Basing your answer on intermolecular force considerations, explain what “like dissolves like” means.

Problem 5QP What is solvation? What factors influence the extent to which solvation occurs? Give two examples of solvation: include one that involves ion-dipole interaction and one in which dispersion forces come into play.

Problem 6QP As you know, some solution processes arc endothermic and others are exothermic. Provide a molecular interpretation for the difference.

Problem 8QP Describe the factors that affect the solubility of a solid in a liquid. What does it mean to say that two liquids are miscible?

Problem 9QP Why is naphthalene (C10H8) more soluble than CsF in benzene?

Explain why ethanol \(\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}\right)\) is not soluble in cyclohexane \(\left(\mathrm{C}_6 \mathrm{H}_{12}\right)\).

Define the following concentration terms and give their units: percent by mass, mole fraction, molarity, molality. Compare their advantages and disadvantages

Problem 14QP Outline the steps required for conversion between molarity, molality, and percent by mass.

Problem 12QP Explain the variations in solubility in water of the listed alcohols: Compound Solubility in water (g/100 g) at 20?C CH3OH ? CH3CH2OH ? CH3CH2CH2OH ? CH3CH2CH2 CH2OH 9 CH3CH2CH2CH2 CH2OH 2.7 Note: ? means that the alcohol and water are completely miscible in all proportions.

Problem 11QP Arrange the following compounds in order of increasing solubility in water: O2, LiCl, Br2, methanol (CH3OH).

Problem 15QP A solution of a particular concentration is prepared at 20°C. Of molarity, molality, percent by mass, and mole fraction, which will change when the solution is heated to 75°C? Explain.

Problem 16QP 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.

Problem 17QP Calculate the molality of each of the following solutions: (a)14.3 g of sucrose (C12H22O11) in 685 g of water, ________________ (b) 7.15 moles of ethylene glycol (C2H6O2) in 3505 g of water.

Calculate the molality of each of the following aqueous solutions: (a) 2.55 M NaCl solution (density of solution = 1.08 g/mL), (b) 45.2 percent by mass KBr solution

Problem 21QP 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.

Problem 19QP Calculate the molalities of the following aqueous solutions: (a) 1.22 M sugar (C12H22O11) solution (density of solution = 1.12 g/mL), (b) 0.87 M NaOH solution (density of solution = 1.04 g/mL). (c) 5.24 M NaHCO3 solution (density of solution 1.19 g/mL).

The concentrated sulfuric acid we use in the laboratory is 98.0 percent \(\mathrm{H}_{2} \mathrm{SO}_{4}\) 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 molality of an \(\mathrm{NH}_3\) solution made up of \(35.0 \mathrm{~g}\) of \(\mathrm{NH}_3\) in \(75.0 \mathrm{~g}\) of water. The density of the solution is \(0.982 \mathrm{~g} / \mathrm{mL}\).

Problem 20QP 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.

Problem 24QP The density of an aqueous solution containing 15.0 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 0.250 mole of ethanol?

Problem 25QP Fish breathe the dissolved air in water through their gills. Assuming the partial pressures of oxygen and nitrogen in air to be 0.20 and 0.80 atm. respectively, calculate the mole fractions of oxygen and nitrogen in the air dissolved in water at 298 K. The solubilities of O2 and N2 in water at 298 K are 1.3 × 10?3 mol/L · atm and 6.8 × 10?4 mol/L · atm, respectively. Comment on your results.

Problem 27QP Discuss the factors that influence the solubility of a gas in a liquid

Problem 29QP What is Henry’s 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 Henry’s law.

Problem 26QP How do the solubilities of most ionic compounds in water change with temperature? With pressure?

Problem 28QP What is thermal pollution? Why is it harmful to aquatic life?

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.

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

Problem 32QP A 3.20-g sample of a salt dissolves in 9.10 g of water to give a saturated solution at 25°C. What is the solubility (in g salt/100 g of H2O) of the salt?

Problem 33QP The solubility of KNO3 is 155 g per 100 g of water at 75°C and 38.0 g at 25?C. What mass (in grams) of KNO3 will crystallize out of solution if exactly 100 g of its saturated solution at 75°C is cooled to 25°C?

Predict whether each vitamin will be water soluble or fat soluble. (See Problem 13.35.)

Problem 35QP The difference between water-soluble and fat-soluble vitamins is their molecular structures. Water-soluble vitamins tend to have multiple polar groups that can interact with water to form hydrogen bonds, whereas fat-soluble vitamins tend to be nonpolar molecules consisting predominately of hydrocarbon chains. This is an example of what is meant by the expression “like dissolves like.” Predict whether vitamin C and vitamin E will be water soluble or fat soluble.

Problem 37QP The solubility of CO2, in water at 25°C 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 Henry's law.

The solubility of \(\mathrm{N}_{2}\) in blood at 37°C and at a partial pressure of 0.80 atm is 5.6 × 10–4 mol/L. A deep-sea diver breathes compressed air with the partial pressure of \(\mathrm{N}_{2}\) equal to 4.0 atm. Assume that the total volume of blood in the body is 5.0 L. Calculate the amount of \(\mathrm{N}_{2}\) gas released (in liters at 37°C and 1 atm) when the diver returns to the surface of the water, where the partial pressure of \(\mathrm{N}_{2}\) is 0.80 atm.

Problem 34QP A 50-g sample of impure KClO3 (solubility = 7.1 g per 100 g H2O at 20°C) is contaminated with 10 percent of KCl (solubility = 25.5 g per 100 g of H2O at 20°C). Calculate the minimum quantity of 20°C water needed to dissolve all the KCl from the sample. How much KClO3 will be left after this treatment? (Assume that the solubilities arc unaffected by the presence of the other compound.)

Problem 39QP A student carried out the following experiment to measure the pressure of carbon dioxide in the space above the carbonated soft drink in a 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 the Henry's law constant for CO2 in water at 25°C is 3.4 × 10?2 mol/L · atm, calculate the pressure of CO2 over the soft drink in the bottle before it was opened. Explain why this pressure is only an estimate of the true value.

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

Problem 42QP Write the equation representing Raoult’s law, and express it in words.

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.

Problem 45QP How is vapor-pressure lowering related to a rise in the boiling point of a solution?

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

Problem 46QP Use a phase diagram to show the difference in freezing points and boiling points between an aqueous urea solution and pure water.

Problem 41QP Give two examples of (a) a volatile liquid and (b) a nonvolatile liquid.

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

Problem 49QP What does it mean when we say that the osmotic pressure of a sample of sea water is 25 atm at a certain temperature?

Problem 47QP What is osmosis? What is a semipermeable membrane?

Problem 50QP Explain why molality is used for boiling-point elevation and freezing-point depression calculations and molarity is used in osmotic pressure calculations.

Problem 52QP What are ion pairs? What effect does ion-pair formation have on the colligative properties of a solution? How does the case 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?

Why is the discussion of the colligative properties of electrolyte solutions more involved than that of nonelectrolyte solutions?

Problem 53QP Indicate which compound in each of the following pairs is more likely to form ion pairs in water: (a) NaCl or Na2SO4, (b) MgCl2 or MgSO4, (c) LiBr or KBr.

What is the van’t Hoff factor? What information does it provide?

How many grams of sucrose \(\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)\) must be added to \(552 \mathrm{~g}\) of water to give a solution with a vapor pressure \(2.0 \mathrm{mmHg}\) less than that of pure water at \(20^{\circ} \mathrm{C}\)? (The vapor pressure of water at \(20^{\circ} \mathrm{C}\) is \(17.5 \mathrm{mmHg}\).)

Problem 55QP For most intravenous injections, great care is taken to ensure that the concentration of solutions to be injected is comparable to that of blood plasma. Explain.

Problem 56QP 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 30°C? (The vapor pressure of water is 31.8 mmHg at 30°C.)

Problem 58QP The vapor pressure of benzene is 100.0 mmHg at 26.1 °C. 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 \(\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)\) and 1-propanol \(\left(\mathrm{C}_{2} \mathrm{H}_{2} \mathrm{OH}\right)\) at 35°C are 100 and 37.6 mmHg, respectively. Assume ideal behavior and calculate the partial pressures of ethanol and 1-propanol at 35°C over a solution of ethanol in 1-propanol, in which the mole fraction of ethanol is 0.300.

Problem 60QP The vapor pressure of ethanol (C2H5OH) at 20°C is 44 mmHg, and the vapor pressure of methanol (CH 3OH) 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 20°C. (b) Calculate the mole fraction of methanol and ethanol in the vapor above this solution at 20°C. (c) Suggest a method for separating the two components of the solution.

Problem 61QP How many grams of urea [(NH2)2CO] must be added to 658 g of water to give a solution with a vapor pressure 2.50 mmHg lower than that of pure water at 30°C? (The vapor pressure of water at 30°C is 31.8 mmHg.)

Problem 62QP What are the boiling point and freezing point of a 3.12 m solution of naphthalene in benzene? (The boiling point and freezing point of benzene are 80.1°C and 5.5°C. respectively.)

An aqueous solution contains the amino acid glycine \(\left(\mathrm{NH}_{2} \mathrm{CH}_{2} \mathrm{COOH}\right)\). Assuming that the acid does not ionize in water, calculate the molality of the solution if it freezes at \(-1.1^{\circ} \mathrm{C}\).

Problem 65QP A solution is prepared by condensing 4.00 L of a gas, measured at 27ºC and 748 mmHg pressure, into 75.0 g of benzene. Calculate the freezing point of this solution.

Problem 64QP 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 -20ºC? Calculate the boiling point of this water-ethylene glycol mixture. (The density of ethylene glycol is 1.11 g /mL.)

Problem 66QP What is the osmotic pressure (in atm) of a 1.57 M aqueous solution of urea [(NH2)2CO] at 27.0°C?

Consider two aqueous solutions, one of sucrose \(\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)\) and the other of nitric acid \(\left(\mathrm{HNO}_{3}\right)\). Both solutions freeze at –1.5°C. What other properties do these solutions have in common?

Which of the following aqueous solutions has (a) the higher boiling point, (b) the higher freezing point, and (c) the lower vapor pressure: \(0.35 \mathrm{~m} \mathrm{CaCl}_2\) or \(0.90 \mathrm{~m}\) urea? Explain. Assume complete dissociation.

Problem 70QP 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.

Arrange the following solutions in order of decreasing freezing point: \(0.10 \mathrm{~m} \mathrm{Na}_{3} \mathrm{PO}_{4}, 0.35 \mathrm{~m} \mathrm{NaCl}\), 0.20 m \(\mathrm{MgCl}_{2}, 0.15 m \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}, 0.15 m \mathrm{CH}_{3} \mathrm{COOH}\).

Problem 72QP At 25°C, 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.

Problem 71QP 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?

Problem 75QP The osmotic pressure of 0.010M Absolutions of CaCl2 and urea at 25°C are 0.605 and 0.245 atm, respectively. Calculate the van't Hoff factor for the CaCl2 solution.

Problem 74QP 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 (37°C). Note that the density of the saline solution is 1.005 g/mL.

Problem 73QP 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?

Problem 76QP Calculate the osmotic pressure of a 0.0500 M MgSO4 solution at 25°C. (Hint: See Table 13.3.)

Problem 78QP Calculate the difference in osmotic pressure (in atm) at the normal body temperature between the blood plasma of a diabetic patient and that of a healthy adult. Assume that the sole difference between the two people is due to the higher glucose level in the diabetic patient. The glucose levels arc 1.75 and 0.84 g/L, respectively. Based on your result, explain why such a patient frequently feels thirsty.

Problem 77QP The tallest trees known arc the redwoods in California. Assuming the height of a redwood to be 105 m (about 350 ft), estimate the osmotic pressure required to push water up to the tree top.

Problem 79QP 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?

Problem 80QP Describe how you would use the osmotic pressure to determine the percent ionization of a weak, monoprotic acid.

Problem 81QP Explain why we cannot use osmotic pressure to determine both molar mass and percent ionization for an unknown monoprotic acid.

Problem 82QP 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 l.56°C. Calculate the molar mass and molecular formula of the solid.(Kf for diphenyl is 8.00°C/m.)

Problem 83QP 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 4.3°C. Calculate the molar mass of the solute and its molecular formula.

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

Problem 87QP 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 20.0°C. Calculate the molar mass of the carbohydrate.

Problem 84QP 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.

Problem 88QP A 0.036 M aqueous nitrous acid (HNO2) solution has an osmotic pressure of 0.93 atm at 25°C. Calculate the percent ionization of the acid.

Problem 85QP 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 25°C. Determine the molar mass of the polymer.

Problem 89QP A 0.100 M aqueous solution of the base HB has an osmotic pressure of 2.83 atm at 25°C. Calculate the percent ionization of the base.

Problem 92QP Describe how hydrophilic and hydrophobic colloids are stabilized in water.

Problem 93QP Describe and give an everyday example of the Tyndall effect.

Problem 91QP What are colloids? Referring to Table 13.5, why is there no colloid in which both the dispersed phase and the dispersing medium are gases?

Problem 94AP Lysozyme is an enzyme that cleaves bacterial cell walls. Asample 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 25°C. 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 25°C is 23.76 mmHg.)

Problem 90QP Hydrofluoric acid (HF) can be used in the fluoridation of water. HF is a weak acid that only partially ionizes in solution. If an aqueous solution that is 0.15 M in HF has an osmotic pressure of 3.9 atm at 25°C, what is the percent ionization of HF at this concentration?

Problem 95AP The blood sugar (glucose) level of a diabetic patient is approximately 0.140 g of glucose/100 mL of blood. Every time the patient ingests 40 g of glucose, her blood glucose level rises to approximately 0.240 g/100 mL of blood. Calculate the number of moles of glucose per milliliter of blood and the total number of moles and grams of glucoec in the blood before and after consumption of glucose. (Assume that the total volume of blood in her body is 5.0 L.)

Problem 96AP Trees in cold climates may be subjected to temperatures as low as ?60°C. Estimate the concentration of an aqueous solution in the body of the tree that would remain unfrozen at this temperature. Is this a reasonable concentration? Comment on your result.

Problem 97AP A cucumber placed in concentrated brine (saltwater) shrivels into a pickle. Explain.

Problem 98AP Two liquids A and B have vapor pressures of 76 and 132 mmHg, respectively, at 25°C. 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?

Problem 99AP Determine the van't Hoff factor of Na3PO4 in a 0.40 m solution whose freezing point is ?2.6°C.

Problem 100AP A 262-mL sample of a sugar solution containing 1.22 g of the sugar has an osmotic pressure of 30.3 mmHg at 35°C. What is the molar mass of the sugar?

Problem 102AP 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 3.9°C. 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. Explain how it works.

Problem 104AP A solution of 1.00 g of anhydrous aluminum chloride (AlCl3) in 50.0 g of water freezes at — 1.11 °C. Does the molar mass determined from this freezing point agree with that calculated from the formula? Why?

Consider the three mercury manometers shown in the diagram. 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?

Explain why reverse osmosis is (theoretically) more desirable as a desalination method than distillation or freezing. What minimum pressure must be applied to seawater at 25°C for reverse osmosis to occur? (Treat seawater as a 0.70 M NaCl solution.)

Problem 107AP The osmotic pressure of blood plasma is approximately 7.5 atm at 37°C. Estimate the total concentration of dissolved species and the freezing point of blood.

Problem 108AP The antibiotic gramicidin A can transport Na+ ions into a certain cell at the rate of 5.0 × 107 Na+ ions/channel · s. Calculate the time in seconds to transport enough Na+ ions to increase its concentration by 8.0 × 10?3 M in a cell whose intracellular volume is 2.0 × 10?10 mL.

A protein has been isolated as a salt with the formula \(N a_{20} P\)(this notation means that there are 20 \(\mathrm{Na}^{+}\) ions associated with a negatively charged protein \(P^{20-}\)). The osmotic pressure of a 10.0-mL solution containing 0.225 g of the protein is 0.257 atm at 25.0°C. (a) Calculate the molar mass of the protein from these data, (b) Calculate the actual molar mass of the protein.

Problem 111AP Hydrogen peroxide with a concentration of 3.0% (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% 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.

What masses of sodium chloride, magnesium chloride, sodium sulfate, calcium chloride, potassium chloride, and sodium bicarbonate are needed to produce 1 L of artificial seawater for an aquarium? The required ionic concentrations are \(\left[\mathrm{Na}^{+}\right]=2.56 \mathrm{M}\), \(\left[\mathrm{K}^{+}\right]=0.0090 \mathrm{M}\), \(\left[\mathrm{Mg}^{2+}\right]=0.054 M\), \(\left[\mathrm{Ca}^{2+}\right]=0.010 \mathrm{M}\), \(\left[\mathrm{HCO}_{3}^{-}\right]\) = 0.0020 M, \(\left[\mathrm{Cl}^{-}\right]=2.60 \mathrm{M}\), \(\left[\mathrm{SO}_{4}^{2-}\right]=0.051 M\).

Problem 112AP State which of the alcohols listed in Problem 13.12 you would expect to be the best solvent for each of the following substances and explain why: (a) I2, (b) KBr, (c) CH3CH2CH2CH2CH3.

Problem 113AP Before a carbonated beverage bottle is scaled, 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?

Problem 114AP Iodine (I2) is only sparingly soluble in water (above left photo). Yet upon the addition of iodide ions (for example, from KI), iodine is converted to the triiodide ion, which readily dissolves (above right photo): Describe the change in solubility of I2, in terms of the change in intermolecular forces.

Problem 110AP 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.

Problem 115AP (a) The root cells of plants contain a solution that is hypertonic in relation to water in the soil. Thus, water can move into the roots by osmosis. Explain why salts such as NaCl and CaCl; spread on roads to melt ice can be harmful to nearby trees, (b) Just before urine leaves the human body, the collecting ducts in the kidney (which contain the urine) pass through a fluid whose salt concentration is considerably greater than is found in the blood and tissues. Explain how this action helps conserve water in the body.

Hemoglobin, the oxygen-transport protein, binds about 1.35 mL of oxygen per gram of the protein. The concentration of hemoglobin in normal blood is 150 g/L blood. Hemoglobin is about 95 percent saturated with \(\mathrm{O}_{2}\) in the lungs and only 74 percent saturated with \(\mathrm{O}_{2}\) in the capillaries. Calculate the volume of \(\mathrm{O}_{2}\) released by hemoglobin when 100 mL of blood flows from the lungs to the capillaries.

Problem 119AP 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.)

Problem 120AP 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. 65°C) is useful as an antifreeze, but it should be removed from the car radiator during the summer season.

Problem 118AP In the apparatus shown, what will happen if the membrane is (a) permeable to both water and the Na+ and Cl? ions. ________________ (b) permeable to water and the Na+ ions but not to the Cl? ions, ________________ (c) permeable to water but not to the Na+ and Cl? ions?

Problem 121AP A mixture of NaCl and sucrose (C12H22O12) 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 23°C. Calculate the mass percent of NaCl in the mixture.

Problem 122AP A 1.32-g sample of a mixture of cyclohexane (C6H12) and naphthalene (CI10,H8) is dissolved in 18.9 g of benzene (C6H6). The freezing point of the solution is 2.2°C. Calculate the mass percent of the mixture. (See Table 13.2 for constants.)

Problem 117AP 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, arc placed under a tightly scaled bell jar at room temperature. What arc the volumes in these two beakers at equilibrium?

Problem 123AP 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?

Problem 124AP A solution contains two volatile liquids A and B. Complete the following table, in which the symbol ? indicates attractive intermolecular forces.

Problem 126AP A mixture of ethanol and 1-propanol behaves ideally at 36°C 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 l-propanol at 36°C arc 108 and 40.0 mmHg, respectively.)

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

Ammonia \(\left(\mathrm{NH}_3\right)\) is very soluble in water, but nitrogen trichloride \(\left(\mathrm{NCl}_3\right)\) is not. Explain.

Problem 128AP 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) is mixed with 500 mL of water, the final volume is less than 1000 mL Why?

Problem 129AP Acetic acid is a weak acid that ionizes in solution as follows: If the freezing point of a 0.106 m CH3COOH solution is ?0.203°C, calculate the percent of the acid that has undergone ionization.

Problem 130AP Which vitamins (see the given structures) do you expect to be water soluble? (See Problem 13.35.)

Problem 131AP Calculate the percent by mass of the solute in each of the following aqueous solutions: (a) 5.75 g of NaBr in 67.9 g of solution, (b) 24.6 g of KCl in 114 g of water. (c) 4.8 g of toluene in 39 g of benzene.

Problem 133AP 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?

Fish in the Antarctic Ocean swim in water at about \(-2^{\circ} \mathrm{C}\). (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 the blood of these fish that, although present in quite low concentrations (\(\leq 0.001 \mathrm{~m}\)), has the ability to prevent the blood from freezing. Suggest a mechanism for its action.

Problem 132AP 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 the ability to form hydrogen bonds. A solution of 3.8 g of CH3COOH in 80 g C6H6 has a freezing point of 3.5°C. Calculate the molar mass of the solute, and suggest what its structure might be. (Hint: Acetic acid molecules can form hydrogen bonds between themselves.)

Problem 135AP Why arc ice cubes (for example, those you sec in the trays in the freezer of a refrigerator) cloudy inside?

Problem 136AP 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?

Problem 137AP Two beakers arc 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.

Problem 138AP (a) Derive the equation relating the molality (m) of a solution to its molarity (M) 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.

Problem 139AP At 27°C. the vapor pressure of pure water is 23.76 mmHg and that of an aqueous solution of urea is 22.98 mmHg. Calculate the molality of urea in the solution.

Problem 140AP 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 fresh water to begin to pass through the membrane? Assume the water to be at 20°C. 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.

Problem 141AP A mixture of liquids A and B exhibits ideal behavior. At 84°C, 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 pressure of pure A and B at 84°C.

Problem 142AP Use Henry's 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: Henry's law can be modified as n= kP. where n is the number of moles of the gas dissolved in the solvent.)

Problem 143AP 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 l.l6g/mL.

Problem 144AP Ringer’s lactate, a solution containing several different salts, is often administered intravenously for the initial treatment of trauma patients. One liter of Ringer’s lactate contains 0.102 mole of sodium chloride, 4 × 10 3 mole of potassium chloride. 1.5 ×10-3 mole of calcium chloride, and 2.8 ×10-2 mole of sodium lactate. Determine the osmotic pressure of this solution at normal body temperature (37°C). Assume no ion pairing. (The formula of the lactate ion is CH3CH2COO?.)

Problem 145AP The diagram here shows vapor pressure curves for pure benzene and a solution of a nonvolatile solute in benzene. Estimate the molality of the solution.

Valinomycin is an antibiotic. It functions by binding \(\mathrm{K}^{+}\)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 different atom is shown at the end of the line). There are as many \(\mathrm{H}\) atoms attached to each \(\mathrm{C}\) atom as necessary to give each \(\mathrm{C}\) atom a total of four bonds. Using the "like dissolves like" principle, explain how the molecule functions. (Hint: The \(-\mathrm{CH}_3\) groups at the two ends of each Y shape are nonpolar.)

Many fluoridation facilities now use fluorosilicic acid instead of sodium fluoride. Fluorosilicic acid typically is distributed as a 23 percent \((1.596 \mathrm{~m})\) aqueous solution. (a) Calculate the van't Hoff factor of fluorosilicic acid given that a 23 percent solution has a freezing point of \(-15.5^{\circ} \mathrm{C}\). (b) The density of 23 percent fluorosilicic acid is \(1.19 \mathrm{~g} / \mathrm{mL}\). Given that the osmotic pressure of the solution at \(25^{\circ} \mathrm{C}\) is 242 atm, calculate the molar mass of fluorosilicic acid.

Problem 147AP Early fluoridation of municipal water supplies was done by dissolving enough sodium fluoride to achieve a 1-ppm concentration of fluoride ion. Convert 1.0 ppm F? to percent by muss F? and molality of NaF.