Coop2                                                                               Dr. R.E.Belford               Chem 1403

  1. Assume that a mixture of a nonvolatile solute and a volatile solvent varies in composition so that the mole fraction of solute varies from 0 to 1. A plot of the vapor pressure vs. mole fraction of solute will:
    1. be linear with positive slope equal to the vapor pressure of the pure solute.
    2. be linear with positive slope equal to the vapor pressure of the pure solvent.
    3. be linear with negative slope equal to the vapor pressure of the pure solute.
    4. be linear with negative slope equal to the vapor pressure of the pure solvent

 

  1. Carboxylic acids are compounds that contain a "CO2H" group. Which of the following carboxylic acids will be the LEAST SOLUBLE in water?

 

 

 

  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.
    1. A 0.10 m solution of NaCl.
    2. A 0.10 m solution of Na2SO4.
    3. A 0.10 m solution of Na3PO4.
    4. A 0.10 m solution of KNO3.
    5. A 0.10 m solution of K2SO4.

 

  1. What is the mole fraction of water in a solution that contains 18 g of water (MW = 18 g/mol) and 92 g of ethyl alcohol (MW = 46 g/mol)?

 

 

 

 

 

 

  1. Commercial, topical solutions of hydrogen peroxide (H2O2, MW = 34 g/mol) are used for disinfecting wounds because H2O2 is a good oxidizing agent (which kills bacteria). What is the MOLARITY of such a solution if it contains 3.0% by mass of H2O2 in water? The density of the solution is 1.00 g/mL.

 

 

 

 

 

 

 

 

  1. What is the vapor pressure of water over a solution prepared by dissolving 100 g of sucrose (MW = 342 g/mol) in 225 g of water (MW = 18.0 g/mol) at 90oC? The vapor pressure of pure water at 90oC is 526 torr.

 

 

 

 

 

 

  1. Potassium iodide reacts with iodine in aqueous solution to form the triiodide ion:

KI(aq) + I2(aq) --> KI3(aq)

What would happen if we added CCl4 (nonpolar) to this reaction?

    1. The KI would tend to dissolve in the CCl4 layer.
    2. The I2 would tend to dissolve in the CCl4 layer.
    3. Both KI and I2 would dissolve in the CCl4 layer.
    4. Neither KI nor I2 would dissolve in the CCl4 layer.
    5. Because CCl4 and water are miscible, no distinct CCl4 layer would form.

 

  1. The average concentration of cholesterol (C27H46O, MW = 386) in human serum is 0.195 g per 100 mL. What is the average molar concentration of cholesterol in human serum?

 

 

 

 

 

 

  1. The melting point of pure benzene is 278.70 K and the molal freezing point depression constant is 4.90 K/molal. When 4.20 g of an unknown solute is added to 100 g of benzene, the freezing point of the solution is 277.60 K. What is the molecular weight of the unknown?

 

 

 

 

 

 

 

 

 

 

10.  A gaseous solute has a concentration of 0.0050 M when the partial pressure is 27 torr.  What is the concentration when the partial pressure increases to 0.27 atm?