Chapter 14 Review Problems                                                       Dr. R.E.Belford              

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

Na₃PO₄, it has the highest molality

2. 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)?

3. 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.

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4. 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 90^oC? The vapor pressure of pure water at 90^oC is 526 torr.

5. 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.

7.   The average concentration of cholesterol (C₂₇H₄₆O, MW = 386) in human serum is 0.195 g per 100 mL. What is the osmotic pressure due to cholesterol at body temperature (37^oC)?

 

 

 

 

8.   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?

 

9.  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?