A solution is made by dissolving 25.8 g urea (CH4N2O), a

Consider Fig. 11.9. According to the caption and picture, water seems to go from one beaker to another. a. Explain why this occurs. b. The explanation in the text uses terms such as vapor pressure and equilibrium. Explain what these have to do with the phenomenon. For example, what is coming to equilibrium? c. Does all the water end up in the second beaker? d. Is water evaporating from the beaker containing the solution? If so, is the rate of evaporation increasing, decreasing, or staying constant? Draw pictures to illustrate your explanations.

Once again, consider Fig. 11.9. Suppose instead of having a nonvolatile solute in the solvent in one beaker, the two beakers contain different volatile liquids. That is, suppose one beaker contains liquid A (Pvap 50 torr) and the other beaker contains liquid B (Pvap 100 torr). Explain what happens as time passes. How is this similar to the first case (shown in the figure)? How is it different?

Assume that you place a freshwater plant into a saltwater solution and examine it under a microscope. What happens to the plant cells? What if you placed a saltwater plant in pure water? Explain. Draw pictures to illustrate your explanations

How does Hsoln relate to deviations from Raoults law? Explain.

You have read that adding a solute to a solvent can both increase the boiling point and decrease the freezing point. A friend of yours explains it to you like this: The solute and solvent can be like salt in water. The salt gets in the way of freezing in that it blocks the water molecules from joining together. The salt acts like a strong bond holding the water molecules together so that it is harder to boil. What do you say to your friend?

You drop an ice cube (made from pure water) into a saltwater solution at 0C. Explain what happens and why

Using the phase diagram for water and Raoults law, explain why salt is spread on the roads in winter (even when it is below freezing)

You and your friend are each drinking cola from separate 2-L bottles. Both colas are equally carbonated. You are able to drink 1 L of cola, but your friend can drink only about half a liter. You each close the bottles and place them in the refrigerator. The next day when you each go to get the colas, whose will be more carbonated and why?

Is molality or molarity dependent on temperature? Explain your answer. Why is molality, and not molarity, used in the equations describing freezing-point depression and boiling-point elevation?

Consider a beaker of salt water sitting open in a room. Over time, does the vapor pressure increase, decrease, or stay the same? Explain.

Rubbing alcohol contains 585 g isopropanol (C3H7OH) per liter (aqueous solution). Calculate the molarity.

What mass of sodium oxalate (Na2C2O4) is needed to prepare 0.250 L of a 0.100 M solution?

What volume of 0.25 M HCl solution must be diluted to prepare 1.00 L of 0.040 M HCl?

What volume of a 0.580 M solution of CaCl2 contains 1.28 g solute?

Calculate the sodium ion concentration when 70.0 mL of 3.0 M sodium carbonate is added to 30.0 mL of 1.0 M sodium bicarbonate.

Write equations showing the ions present after the following strong electrolytes are dissolved in water. a. HNO3 d. SrBr2 g. NH4NO3 b. Na2SO4 e. KClO4 h. CuSO4 c. Al(NO3)3 f. NH4Br i. NaOH

Rationalize the temperature dependence of the solubility of a gas in water in terms of the kinetic molecular theory.

The weak electrolyte NH3(g) does not obey Henrys law. Why? O2(g) obeys Henrys law in water but not in blood (an aqueous solution). Why?

The two beakers in the sealed container illustrated below contain pure water and an aqueous solution of a volatile solute. Water Aqueous solution If the solute is less volatile than water, explain what will happen to the volumes in the two containers as time passes

The following plot shows the vapor pressure of various solutions of components A and B at some temperature. 0 PA 0 PB 0 1 Mole fraction B Vapor pressure (torr) Which of the following statements is false concerning solutions of A and B? a. The solutions exhibit negative deviations from Raoults law. b. Hsoln for the solutions should be exothermic. c. The intermolecular forces are stronger in solution than in either pure A or pure B. d. Pure liquid B is more volatile than pure liquid A. e. The solution with B 0.6 will have a lower boiling point than either pure A or pure B.

When pure methanol is mixed with water, the resulting solution feels warm. Would you expect this solution to be ideal? Explain.

Detergent molecules can stabilize the emulsion of oil in water as well as remove dirt from soiled clothes. A typical detergent is sodium dodecylsulfate, or SDS, and it has a formula of CH3(CH2)10CH2SO4 Na. In aqueous solution, SDS suspends oil or dirt by forming small aggregates of detergent anions called micelles. Propose a structure for micelles.

For an acid or a base, when is the normality of a solution equal to the molarity of the solution and when are the two concentration units different?

In order for sodium chloride to dissolve in water, a small amount of energy must be added during solution formation. This is not energetically favorable. Why is NaCl so soluble in water?

Which of the following statements is(are) true? Correct the false statements. a. The vapor pressure of a solution is directly related to the mole fraction of solute. b. When a solute is added to water, the water in solution has a lower vapor pressure than that of pure ice at 0C. c. Colligative properties depend only on the identity of the solute and not on the number of solute particles present. d. When sugar is added to water, the boiling point of the solution increases above 100C because sugar has a higher boiling point than water

Is the following statement true or false? Explain your answer. When determining the molar mass of a solute using boiling-point or freezing-point data, camphor would be the best solvent choice of all of the solvents listed in Table 11.5.

Explain the terms isotonic solution, crenation, and hemolysis.

What is ion pairing?

A solution of phosphoric acid was made by dissolving 10.0 g H3PO4 in 100.0 mL water. The resulting volume was 104 mL. Calculate the density, mole fraction, molarity, and molality of the solution. Assume water has a density of 1.00 g/cm3

An aqueous antifreeze solution is 40.0% ethylene glycol (C2H6O2) by mass. The density of the solution is 1.05 g/cm3 . Calculate the molality, molarity, and mole fraction of the ethylene glycol.

Common commercial acids and bases are aqueous solutions with the following properties: Calculate the molarity, molality, and mole fraction of each of the preceding reagents

In lab you need to prepare at least 100 mL of each of the following solutions. Explain how you would proceed using the given information. a. 2.0 m KCl in water (density of H2O 1.00 g/cm3 ) b. 15% NaOH by mass in water (d 1.00 g/cm3 ) c. 25% NaOH by mass in CH3OH (d 0.79 g/cm3 ) d. 0.10 mole fraction of C6H12O6 in water (d 1.00 g/cm3 ) 33

A solution is prepared by mixing 25 mL pentane (C5H12, d 0.63 g/cm3 ) with 45 mL hexane (C6H14, d 0.66 g/cm3 ). Assuming that the volumes add on mixing, calculate the mass percent, mole fraction, molality, and molarity of the pentane.

A solution is prepared by mixing 50.0 mL toluene (C6H5CH3, d 0.867 g/cm3 ) with 125 mL benzene (C6H6, d 0.874 g/cm3 ). Assuming that the volumes add on mixing, calculate the mass percent, mole fraction, molality, and molarity of the toluene.

A bottle of wine contains 12.5% ethanol by volume. The density of ethanol (C2H5OH) is 0.789 g/cm3 . Calculate the concentration of ethanol in wine in terms of mass percent and molality

Calculate the molarity and mole fraction of acetone in a 1.00 m solution of acetone (CH3COCH3) in ethanol (C2H5OH). (Density of acetone 0.788 g/cm3 ; density of ethanol 0.789 g/cm3 .) Assume that the volumes of acetone and ethanol add.

A 1.37 M solution of citric acid (H3C6H5O7) in water has a density of 1.10 g/cm3 . Calculate the mass percent, molality, mole fraction, and normality of the citric acid. Citric acid has three acidic protons.

Calculate the normality of each of the following solutions. a. 0.250 M HCl b. 0.105 M H2SO4 c. 5.3 102 M H3PO4 d. 0.134 M NaOH e. 0.00521 M Ca(OH)2 What is the equivalent mass for each of the acids or bases listed above?

The lattice energy* of NaI is 686 kJ/mol, and the enthalpy of hydration is 694 kJ/mol. Calculate the enthalpy of solution per mole of solid NaI. Describe the process to which this enthalpy change applies.

a. Use the following data to calculate the enthalpy of hydration for calcium chloride and calcium iodide.

Based on your answers to part a, which ion, Cl or I, is more strongly attracted to water?

Although Al(OH)3 is insoluble in water, NaOH is very soluble. Explain in terms of lattice energies

The high melting points of ionic solids indicate that a lot of energy must be supplied to separate the ions from one another. How is it possible that the ions can separate from one another when soluble ionic compounds are dissolved in water, often with essentially no temperature change?

Which solvent, water or carbon tetrachloride, would you choose to dissolve each of the following? a. KrF2 e. MgF2 b. SF2 f. CH2O c. SO2 g. CH2PCH2 d. CO2

Which solvent, water or hexane (C6H14), would you choose to dissolve each of the following?

For each of the following pairs, predict which substance would be more soluble in water. a. NH3 or PH3 b. CH3CN or CH3CH3 c. CH3COOH or CH3OCOOCH3

Which ion in each of the following pairs would you expect to be more strongly hydrated? Why? a. Na or Mg2 d. F or Br b. Mg2 or Be2 e. Cl or ClO4  c. Fe2 or Fe3 f. ClO4  or SO4

Rationalize the trend in water solubility for the following simple alcohols

In flushing and cleaning columns used in liquid chromatography to remove adsorbed contaminants, a series of solvents is used. Hexane (C6H14), chloroform (CHCl3), methanol (CH3OH), and water are passed through the column in that order. Rationalize the order in terms of intermolecular forces and the mutual solubility (miscibility) of the solvents.

The solubility of nitrogen in water is 8.21 104 mol/L at 0C when the N2 pressure above water is 0.790 atm. Calculate the Henrys law constant for N2 in units of mol/L atm for Henrys law in the form C kP, where C is the gas concentration in mol/L. Calculate the solubility of N2 in water when the partial pressure of nitrogen above water is 1.10 atm at 0C.

Calculate the solubility of O2 in water at a partial pressure of O2 of 120 torr at 25C. The Henrys law constant for O2 is 1.3 103 mol/L atm for Henrys law in the form C kP, where C is the gas concentration (mol/L). V

Glycerin, C3H8O3, is a nonvolatile liquid. What is the vapor pressure of a solution made by adding 164 g glycerin to 338 mL H2O at 39.8C? The vapor pressure of pure water at 39.8C is 54.74 torr and its density is 0.992 g/cm3

The vapor pressure of a solution containing 53.6 g glycerin (C3H8O3) in 133.7 g ethanol (C2H5OH) is 113 torr at 40C. Calculate the vapor pressure of pure ethanol at 40C assuming that glycerin is a nonvolatile, nonelectrolyte solute in ethanol.

The normal boiling point of methanol is 64.7C. A solution containing a nonvolatile solute dissolved in methanol has a vapor pressure of 710.0 torr at 64.7C. What is the mole fraction of methanol in this solution?

At a certain temperature, the vapor pressure of pure benzene (C6H6) is 0.930 atm. A solution was prepared by dissolving 10.0 g of a nondissociating, nonvolatile solute in 78.11 g of benzene at that temperature. The vapor pressure of the solution was found to be 0.900 atm. Assuming the solution behaves ideally, determine the molar mass of the solute

A solution is made by dissolving 25.8 g urea (CH4N2O), a nonelectrolyte, in 275 g water. Calculate the vapor pressures of this solution at 25C and 45C. (The vapor pressure of pure water is 23.8 torr at 25C and 71.9 torr at 45C.)

A solution of sodium chloride in water has a vapor pressure of 19.6 torr at 25C. What is the mole fraction of solute particles in this solution? What would be the vapor pressure of this solution at 45C? The vapor pressure of pure water is 23.8 torr at 25C and 71.9 torr at 45C and assume sodium chloride exists as Na and Cl ions in solution

Pentane (C5H12) and hexane (C6H14) form an ideal solution. At 25C the vapor pressures of pentane and hexane are 511 and 150. torr, respectively. A solution is prepared by mixing 25 mL pentane (density, 0.63 g/mL) with 45 mL hexane (density, 0.66 g/mL). a. What is the vapor pressure of the resulting solution? b. What is the composition by mole fraction of pentane in the vapor that is in equilibrium with this solution?

A solution is prepared by mixing 0.0300 mol CH2Cl2 and 0.0500 mol CH2Br2 at 25C. Assuming the solution is ideal, calculate the composition of the vapor (in terms of mole fractions) at 25C. At 25C, the vapor pressures of pure CH2Cl2 and pure CH2Br2 are 133 and 11.4 torr, respectively.

What is the composition of a methanol (CH3OH)propanol (CH3CH2CH2OH) solution that has a vapor pressure of 174 torr at 40C? At 40C, the vapor pressures of pure methanol and pure propanol are 303 and 44.6 torr, respectively. Assume the solution is ideal.

Benzene and toluene form an ideal solution. Consider a solution of benzene and toluene prepared at 25C. Assuming the mole fractions of benzene and toluene in the vapor phase are equal, calculate the composition of the solution. At 25C the vapor pressures of benzene and toluene are 95 and 28 torr, respectively.

Which of the following will have the lowest total vapor pressure at 25C?

Which of the choices in Exercise 61 has the highest vapor pressure?

A solution is made by mixing 50.0 g acetone (CH3COCH3) and 50.0 g methanol (CH3OH). What is the vapor pressure of this solution at 25C? What is the composition of the vapor expressed as a mole fraction? Assume ideal solution and gas behavior. (At 25C the vapor pressures of pure acetone and pure methanol are 271 and 143 torr, respectively.) The actual vapor pressure of this solution is 161 torr. Explain any discrepancies.

The vapor pressures of several solutions of waterpropanol (CH3CH2CH2OH) were determined at various compositions, with the following data collected at 45C:

A solution is prepared by dissolving 27.0 g urea, (NH2)2CO, in 150.0 g water. Calculate the boiling point of the solution. Urea is a nonelectrolyte.

A 2.00-g sample of a large biomolecule was dissolved in 15.0 g carbon tetrachloride. The boiling point of this solution was determined to be 77.85C. Calculate the molar mass of the biomolecule. For carbon tetrachloride, the boiling-point constant is 5.03C kg/mol, and the boiling point of pure carbon tetrachloride is 76.50C.

What mass of glycerin (C3H8O3), a nonelectrolyte, must be dissolved in 200.0 g water to give a solution with a freezing point of 1.50C?

The freezing point of t-butanol is 25.50C and Kf is 9.1C kg/mol. Usually t-butanol absorbs water on exposure to air. If the freezing point of a 10.0-g sample of t-butanol is 24.59C, how many grams of water are present in the sample?

Calculate the freezing point and boiling point of an antifreeze solution that is 50.0% by mass of ethylene glycol (HOCH2CH2OH) in water. Ethylene glycol is a nonelectrolyte.

What volume of ethylene glycol (C2H6O2), a nonelectrolyte, must be added to 15.0 L water to produce an antifreeze solution with a freezing point 25.0C? What is the boiling point of this solution? (The density of ethylene glycol is 1.11 g/cm3 , and the density of water is 1.00 g/cm3 .)

Reserpine is a natural product isolated from the roots of the shrub Rauwolfia serpentina. It was first synthesized in 1956 by Nobel Prize winner R. B. Woodward. It is used as a tranquilizer and sedative. When 1.00 g reserpine is dissolved in 25.0 g camphor, the freezing-point depression is 2.63C (Kf for camphor is 40.C kg/mol). Calculate the molality of the solution and the molar mass of reserpine.

A solution contains 3.75 g of a nonvolatile pure hydrocarbon in 95 g acetone. The boiling points of pure acetone and the solution are 55.95C and 56.50C, respectively. The molal boilingpoint constant of acetone is 1.71C kg/mol. What is the molar mass of the hydrocarbon?

a. Calculate the freezing-point depression and osmotic pressure at 25C of an aqueous solution containing 1.0 g/L of a protein (molar mass 9.0 104 g/mol) if the density of the solution is 1.0 g/cm3

b. Considering your answer to part a, which colligative property, freezing-point depression or osmotic pressure, would be better used to determine the molar masses of large molecules? Explain

A 0.15-g sample of a purified protein is dissolved in water to give 2.0 mL of solution. The osmotic pressure is found to be 18.6 torr at 25C. Calculate the proteins molar mass.

How would you prepare 1.0 L of an aqueous solution of sucrose (C12H22O11) having an osmotic pressure of 15 atm at a temperature of 22C? Sucrose is a nonelectrolyte

How would you prepare 1.0 L of an aqueous solution of sodium chloride having an osmotic pressure of 15 atm at 22C? Assume sodium chloride exists as Na and Cl ions in solution.

Consider the following solutions: 0.010 m Na3PO4 in water 0.020 m CaBr2 in water 0.020 m KCl in water 0.020 m HF in water (HF is a weak acid.) a. Assuming complete dissociation of the soluble salts, which solution(s) would have the same boiling point as 0.040 m C6H12O6 in water? C6H12O6 is a nonelectrolyte. b. Which solution would have the highest vapor pressure at 28C? c. Which solution would have the largest freezing-point depression?

From the following: pure water solution of C12H22O11 (m 0.01) in water solution of NaCl (m 0.01) in water solution of CaCl2 (m 0.01) in water choose the one with the a. highest freezing point. d. lowest boiling point. b. lowest freezing point. e. highest osmotic pressure. c. highest boiling point.

Calculate the freezing point and the boiling point of each of the following solutions. (Assume complete dissociation.) a. 5.0 g NaCl in 25 g H2O b. 2.0 g Al(NO3)3 in 15 g H2O

A water desalination plant is set up near a salt marsh containing water that is 0.10 M NaCl. Calculate the minimum pressure that must be applied at 20.C to purify the water by reverse osmosis. Assume NaCl is completely dissociated.

Calculate the freezing point and the boiling point of each of the following aqueous solutions. (Assume complete dissociation.) a. 0.050 m MgCl2 b. 0.050 m FeCl3

Calculate the freezing point and the boiling point of each of the following solutions using the observed vant Hoff factors in Table 11.6. a. 0.050 m MgCl2 b. 0.050 m FeCl3

Use the following data for three aqueous solutions of CaCl2 to calculate the apparent value of the vant Hoff factor.

The freezing-point depression of a 0.091 m solution of CsCl is 0.320C. The freezing-point depression of a 0.091 m solution of CaCl2 is 0.440C. In which solution does ion association appear to be greater? Explain.

In the winter of 1994, record low temperatures were registered throughout the United States. For example, in Champaign, Illinois, a record low of 29F was registered. At this temperature can salting icy roads with CaCl2 be effective in melting the ice? a. Assume i 3.00 for CaCl2. b. Assume the average value of i from Exercise 83. (The solubility of CaCl2 in cold water is 74.5 g per 100.0 g water.)

A 0.500-g sample of a compound is dissolved in enough water to form 100.0 mL of solution. This solution has an osmotic pressure of 2.50 atm at 25C. If each molecule of the solute dissociates into two particles (in this solvent), what is the molar mass of this solute?

The solubility of benzoic acid (HC7H5O2), is 0.34 g/100 mL in water at 25C and is 10.0 g/100 mL in benzene (C6H6) at 25C. Rationalize this solubility behavior. (Hint: Benzoic acid forms a dimer in benzene.) Would benzoic acid be more or less soluble in a 0.1 M NaOH solution than it is in water? Explain.

A forensic chemist is given a white solid that is suspected of being pure cocaine (C17H21NO4, molar mass 303.35 g/mol). She dissolves 1.22 0.01 g of the solid in 15.60 0.01 g benzene. The freezing point is lowered by 1.32 0.04C. a. What is the molar mass of the substance? Assuming that the percent uncertainty in the calculated molar mass is the same as the percent uncertainty in the temperature change, calculate the uncertainty in the molar mass. b. Could the chemist unequivocally state that the substance is cocaine? For example, is the uncertainty small enough to distinguish cocaine from codeine (C18H21NO3, molar mass 299.36 g/mol)? c. Assuming that the absolute uncertainties in the measurements of temperature and mass remain unchanged, how could the chemist improve the precision of her results?

Thyroxine, an important hormone that controls the rate of metabolism in the body, can be isolated from the thyroid gland. When 0.455 g thyroxine is dissolved in 10.0 g benzene, the freezing point of the solution is depressed by 0.300C. What is the molar mass of thyroxine? See Table 11.5.

An aqueous solution of 10.00 g of catalase, an enzyme found in the liver, has a volume of 1.00 L at 27C. The solutions osmotic pressure at 27C is found to be 0.745 torr. Calculate the molar mass of catalase

If the human eye has an osmotic pressure of 8.00 atm at 25C, what concentration of solute particles in water will provide an isotonic eyedrop solution (a solution with equal osmotic pressure)?

Erythrocytes are red blood cells containing hemoglobin. In a saline solution they shrivel when the salt concentration is high and swell when the salt concentration is low. In a 25C aqueous solution of NaCl, whose freezing point is 0.406C, erythrocytes neither swell nor shrink. If we want to calculate the osmotic pressure of the solution inside the erythrocytes under these conditions, what do we need to assume? Why? Estimate how good (or poor) of an assumption this is. Make this assumption and calculate the osmotic pressure of the solution inside the erythrocytes.

Patients undergoing an upper gastrointestinal tract laboratory test are typically given an X-ray contrast agent that aids with the radiologic imaging of the anatomy. One such contrast agent is sodium diatrizoate, a nonvolatile water-soluble compound. A 0.378 m solution is prepared by dissolving 38.4 g sodium diatrizoate (NaDTZ) in 1.60  102 mL water at 31.2C (the density of water at 31.2C is 0.995 g/mL). What is the molar mass of sodium diatrizoate? What is the vapor pressure of this solution if the vapor pressure of pure water at 31.2C is 34.1 torr? 9

Specifications for lactated Ringers solution, which is used for intravenous (IV) injections, are as follows to reach 100. mL of solution: 285315 mg Na 14.117.3 mg K 4.96.0 mg Ca2 368408 mg Cl 231261 mg lactate, C3H5O3 a. Specify the amount of NaCl, KCl, CaCl2 2H2O, and NaC3H5O3 needed to prepare 100. mL lactated Ringers solution. b. What is the range of the osmotic pressure of the solution at 37C, given the preceding specifications? A

In a coffee-cup calorimeter, 1.60 g NH4NO3 was mixed with 75.0 g water at an initial temperature 25.00C. After dissolution the salt, the final temperature of the calorimeter contents was 23.34C. a. Assuming the solution has a heat capacity of 4.18 J/g C, and assuming no heat loss to the calorimeter, calculate the enthalpy of solution (Hsoln) for the dissolution of NH4NO3 in units of kJ/mol. b. If the enthalpy of hydration for NH4NO3 is 630. kJ/mol, calculate the lattice energy of NH4NO3. 96.

In Exercise 118 in Chapter 5, the pressure of CO2 in a bottle of sparkling wine was calculated assuming that the CO2 was insoluble in water. This was a bad assumption. Redo this problem by assuming that CO2 obeys Henrys law. Use the data given in that problem to calculate the partial pressure of CO2 in the gas phase and the solubility of CO2 in the wine at 25C. The Henrys law constant for CO2 is 3.1  102 mol/L atm at 25C with Henrys law in the form C  kP, where C is the concentration of the gas in mol/L. 97

Explain the following on the basis of the behavior of atoms and/or ions. a. Cooking with water is faster in a pressure cooker than in an open pan. b. Salt is used on icy roads. c. Melted sea ice from the Arctic Ocean produces fresh water. d. CO2(s) (dry ice) does not have a normal boiling point under normal atmospheric conditions, even though CO2 is a liquid in fire extinguishers. e. Adding a solute to a solvent extends the liquid phase over a larger temperature range

The term proof is defined as twice the percent by volume of pure ethanol in solution. Thus, a solution that is 95% (by volume) ethanol is 190 proof. What is the molarity of ethanol in a 92 proof ethanolwater solution? Assume the density of ethanol, C2H5OH, is 0.79 g/cm3 and the density of water is 1.0 g/cm3 .

At 25C, the vapor in equilibrium with a solution containing carbon disulfide and acetonitrile has a total pressure of 263 torr and is 85.5 mole percent carbon disulfide. What is the mole fraction of carbon disulfide in the solution? At 25C, the vapor pressure of carbon disulfide is 375 torr. Assume the solution and vapor exhibit ideal behavior.

If the fluid inside a tree is about 0.1 M more concentrated in solute than the groundwater that bathes the roots, how high will a column of fluid rise in the tree at 25C? Assume that the density of the fluid is 1.0 g/cm3 . (The density of mercury is 13.6 g/cm3 .)

An unknown compound contains only carbon, hydrogen, and oxygen. Combustion analysis of the compound gives mass percents of 31.57% C and 5.30% H. The molar mass is determined by measuring the freezing-point depression of an aqueous solution. A freezing point of 5.20C is recorded for a solution made by dissolving 10.56 g of the compound in 25.0 g water. Determine the empirical formula, molar mass, and molecular formula of the compound. Assume that the compound is a nonelectrolyte.

Consider the following: What would happen to the level of liquid in the two arms if the semipermeable membrane separating the two liquids were permeable to a. H2O only? b. H2O, Na, and Cl?

Consider an aqueous solution containing sodium chloride that has a density of 1.01 g/mL. Assume the solution behaves ideally. The freezing point of this solution at 1.0 atm is 1.28C. Calculate the percent composition of this solution (by mass).

What stabilizes a colloidal suspension? Explain why adding heat or adding an electrolyte can cause the suspended particles to settle out

The freezing point of an aqueous solution is 2.79C. a. Determine the boiling point of this solution. b. Determine the vapor pressure (in mm Hg) of this solution at 25C (the vapor pressure of pure water at 25C is 23.76 mm Hg). c. Explain any assumptions you make in solving parts a and b. 10

The vapor pressure of pure benzene is 750.0 torr and the vapor pressure of toluene is 300.0 torr at a certain temperature. You make a solution by pouring some benzene with some toluene. You then place this solution in a closed container and wait for the vapor to come into equilibrium with the solution. Next, you condense the vapor. You put this liquid (the condensed vapor) in a closed container and wait for the vapor to come into equilibrium with the solution. You then condense this vapor and find the mole fraction of benzene in this vapor to be 0.714. Determine the mole fraction of benzene in the original solution assuming the solution behaves ideally

Liquid A has vapor pressure x, and liquid B has vapor pressure y. What is the mole fraction of the liquid mixture if the vapor above the solution is 30.% A by moles? 50.% A? 80.% A? (Calculate in terms of x and y.) Liquid A has vapor pressure x, liquid B has vapor pressure y. What is the mole fraction of the vapor above the solution if the liquid mixture is 30.% A by moles? 50.% A? 80.% A? (Calculate in terms of x and y.)

Plants that thrive in salt water must have internal solutions (inside the plant cells) that are isotonic with (have the same osmotic pressure as) the surrounding solution. A leaf of a saltwater plant is able to thrive in an aqueous salt solution (at 25C) that has a freezing point equal to 0.621C. You would like to use this information to calculate the osmotic pressure of the solution in the cell. a. In order to use the freezing-point depression to calculate osmotic pressure, what assumption must you make (in addition to ideal behavior of the solutions, which we will assume)? b. Under what conditions is the assumption (in part a) reasonable? c. Solve for the osmotic pressure (at 25C) of the solution in the plant cell. d. The plant leaf is placed in an aqueous salt solution (at 25C) that has a boiling point of 102.0C. What will happen to the plant cells in the leaf?

You make 20.0 g of a sucrose (C12H22O11) and NaCl mixture and dissolve it in 1.00 kg water. The freezing point of this solution is found to be 0.426C. Assuming ideal behavior, calculate the mass percent composition of the original mixture, and the mole fraction of sucrose in the original mixture

An aqueous solution is 1.00% NaCl by mass and has a density of 1.071 g/cm3 at 25C. The observed osmotic pressure of this solution is 7.83 atm at 25C. a. What fraction of the moles of NaCl in this solution exist as ion pairs? b. Calculate the freezing point that would be observed for this solution

The vapor in equilibrium with a pentanehexane solution at 25C has a mole fraction of pentane equal to 0.15 at 25C. What is the mole fraction of pentane in the solution? (See Exercise 57 for the vapor pressures of the pure liquids.)

A solid consists of a mixture of NaNO3 and Mg(NO3)2. When 6.50 g of this solid is dissolved in 50.0 g water, the freezing point is lowered by 5.40C. What is the composition of the solid (by mass)? Assume ideal behavior.

A 1.60-g sample of a mixture of naphthalene (C10H8) and anthracene (C14H10) is dissolved in 20.0 g benzene (C6H6). The freezing point of the solution is 2.81C. What is the composition as mass percent of the sample mixture? The freezing point of benzene is 5.51C and Kf is 5.12C kg/mol.

A solid mixture contains MgCl2 and NaCl. When 0.5000 g of this solid is dissolved in enough water to form 1.000 L of solution, the osmotic pressure at 25.0C is observed to be 0.3950 atm. What is the mass percent of MgCl2 in the solid? (Assume ideal behavior for the solution.)

Formic acid (HCO2H) is a monoprotic acid that ionizes only partially in aqueous solutions. A 0.10 M formic acid solution is 4.2% ionized. Assuming that the molarity and molality of the solution are the same, calculate the freezing point and the boiling point of 0.10 M formic acid.

You have a solution of two volatile liquids, A and B (assume ideal behavior). Pure liquid A has a vapor pressure of 350.0 torr and pure liquid B has a vapor pressure of 100.0 torr at the temperature of the solution. The vapor at equilibrium above the solution has double the mole fraction of substance A that the solution does. What is the mole fraction of liquid A in the solution?

In some regions of the southwest United States, the water is very hard. For example, in Las Cruces, New Mexico, the tap water contains about 560 g of dissolved solids per milliliter. Reverse osmosis units are marketed in this area to soften water. A typical unit exerts a pressure of 8.0 atm and can produce 45 L water per day. a. Assuming all of the dissolved solids are MgCO3 and assuming a temperature of 27C, what total volume of water must be processed to produce 45 L pure water? b. Would the same system work for purifying seawater? (Assume seawater is 0.60 M NaCl.)

Creatinine, C4H7N3O, is a by-product of muscle metabolism, and creatinine levels in the body are known to be a fairly reliable indicator of kidney function. The normal level of creatinine in the blood for adults is approximately 1.0 mg per deciliter (dL) of blood. If the density of blood is 1.025 g/mL, calculate the molality of a normal creatinine level in a 10.0-mL blood sample. What is the osmotic pressure of this solution at 25.0C?

An aqueous solution containing 0.250 mol Q, a strong electrolyte, in 5.00 102 g water freezes at 2.79C. What is the vant Hoff factor for Q? The molal freezing-point depression constant for water is 1.86C kg/mol. What is the formula of Q if it is 38.68% chlorine by mass and there are twice as many anions as cations in one formula unit of Q?

Anthraquinone contains only carbon, hydrogen, and oxygen. When 4.80 mg anthraquinone is burned, 14.2 mg CO2 and 1.65 mg H2O are produced. The freezing point of camphor is lowered by 22.3C when 1.32 g anthraquinone is dissolved in 11.4 g camphor. Determine the empirical and molecular formulas of anthraquinone.

Using the following information, identify the strong electrolyte whose general formula is Ignore the effect of interionic attractions in the solution. a. An is a common oxyanion. When 30.0 mg of the anhydrous sodium salt containing this oxyanion (NanA, where n 1, 2, or 3) is reduced, 15.26 mL of 0.02313 M reducing agent is required to react completely with the NanA present. Assume a 1:1 mole ratio in the reaction. Mx1A2y zH2O b. The cation is derived from a silvery white metal that is relatively expensive. The metal itself crystallizes in a body-centered cubic unit cell and has an atomic radius of 198.4 pm. The solid, pure metal has a density of 5.243 g/cm3 . The oxidation number of M in the strong electrolyte in question is 3. c. When 33.45 mg of the compound is present (dissolved) in 10.0 mL of aqueous solution at 25C, the solution has an osmotic pressure of 558 torr. *