Page 1 of 3 CHM 11500 PARTE Week 16 1. Which of the following aqueous solutions will boil at the highest temperature? Note: all of the salts listed below are completely soluble in water. a. A 0.10 m solution of NaCl. b. A 0.10 m solution of Na2SO4. c. A 0.10 m solution of Na3PO4. d. A 0.10 m solution of KNO3. e. A 0.10 m solution of K2SO4. 2. Which of the following concentration units changes with temperature? a. molality b. mole fraction c. molarity d. mass percent 3. Which of the following species would be most soluble in a nonpolar solvent such as carbon tetrachloride? a. sodium chloride b. water c. molecular iodine (I2) d. triodide ion (I3-) e. KMnO4 4. What is the mole fraction of water in a solution that contains 18 g of water (MM = 18 g/mol) and 92 g of ethyl alcohol (MM = 46 g/mol)? a. 0.16 b. 0.33 c. 0.50 d. 0.87 e. 11Page 2 of 3 5. What is the vapor pressure of water over a solution prepared by dissolving 100 g of sucrose (MM = 342 g/mol) in 225 g of water (MM = 18 g/mol) at 90oC? The vapor pressure of pure water at 90oC is 526 torr. a. 0.079 torr b. 514 torr c. 539 torr d. 1184 torr e. 2368 torr 6. Which of the following solutions would have the highest freezing point? Note: all of these salts are completely soluble in water. a. a 0.10 molal solution of sodium chloride (NaCl) b. a 0.10 molal solution of magnesium chloride (MgCl2) c. a 0.10 molal solution of iron chloride (FeCl3) d. a 0.10 molal solution of sodium sulfate (Na2SO4) e. a 0.10 molal solution of ammonium phosphate ((NH4)3PO4) 7. The average concentration of cholesterol (C27H46O, MM = 386 g/mol) in human serum is 0.195 g per 100 mL. What is the average molar concentration of cholesterol in human serum? a. 5.05 x 10-2 b. 5.05 x 10-3 c. 4.51 x 10-3 d. 5.05 x 10-4 8. What is the mole fraction of water in a solution containing 36 g of water (MM = 18 g/mol) and 60 g of acetic acid (MM = 60 g/mol)? 9. When 0.534 g of a solute is dissolved in 15 g of water (MM = 18 g/mol) the freezing point if water is reduced from 0oC to -1.57oC. The freezing-point depression constant for water is 1.85oC kg/mol. What is the molal concentration of the solute in this solution?Page 3 of 3 10. What is the molar mass of the solute in the solution in the preceding question? 11. Which of the following best explains why it takes LONGER to cook an egg in Denver, Colorado (atmospheric pressure = 720 mmHg) than in West Lafayette, Indiana (atmospheric pressure = 755 mmHg)? a. The boiling point of water is lower in Denver than in West Lafayette. b. The boiling point of water is higher in Denver than in West Lafayette. c. There is less hydrogen bonding between water molecules in Denver than in West Lafayette. d. The molar mass of water in Denver is higher than in West Lafayette. e. The shape of water molecules in Denver is different than in West Lafayette. 12. Calculate the molal concentration of ethyl alcohol in a solution that contains 4.6 grams of ethyl alcohol (MM = 46 g/mol) and 500 grams of water (MM = 18 g/mol). 13. When 0.795 grams of a non-volatile solute are added to 13 grams of water, the freezing point of water is reduced by 1.89oC. Calculate the molar mass of the solute. (For water: Kf = 1.86 oC/m). 14. In large quantities, the nicotine in tobacco is a deadly poison. Calculate the molar mass of nicotine if a solution containing 3.62 g of nicotine in 73.4 g of water (Kf = 1.85oC/m) gives a freezing point 0.563oC below the freezing point of pure water. 15. Which freezes at a LOWER temperature, hard water or soft water? Explain your reasoning. 16. Calculate the total vapor pressure of a solution prepared by dissolving 0.45 mol of pentane (MM = 72.2 g/mol) in 0.95 mol of hexane (MM = 86.2 g/mol) if the vapor pressures for pure pentane and hexane are 511 torr and 150 torr,