Exam 1 Review Worksheet
Supplemental Instruction
Iowa State University / Leader: / Lillian Howard
Course: / 178 (B)
Instructor: / Dr. Burnett
Date: / 2/11/13

1.  A solution contains 10.0 g of KOH and 900 mL of water. The volume of the solution is 904.7 mL.

  1. Which component is the solute? Solvent?

Solute= KOH Solvent= H2O

  1. What is the molarity of the solution?

0.197 mol/L

  1. What is the mass percentage of KOH?

1.10%

  1. What is the mole fraction of KOH?

3.55·10-3

  1. What is the molality of the solution?

0.198 m

2.  Nitric acid has a density of 1.42 g/mL and is 16 M. Calculate the percent HNO3 by mass in solution.

1.42·103 x 100 = 71%

1.0·103

3.  Calculate molarity of a solution that contains 18% HCl by mass and has a density of 1.05 g/mL.

5.18 M

4.  How many grams of ethylene glycol (C2H6O2) must be added to 1.00 kg of water to produce a solution that freezes at -5.00˚C? Kf = 1.86˚C/m

167g C2H6O2

5.  A solution is formed by dissolving 10.0g of KCl in 500.0 g of water.

  1. What is the vapor pressure of a solution at 25˚C if the vapor pressure of water is 23.8 torr at 25˚C?

23.6

  1. What is the boiling point elevation? Kb for water is 0.52˚C/m.

0.27 ˚C

  1. What is the freezing point depression? Kf for water is 1.86˚C/m.

1.0˚C

  1. What is the osmotic pressure of the solution? Volume is .500 L

13.1 atm

6.  A 1.0 L container initially holds 0.015 mol of H2 and 0.020 mole of I2 at 721 K. What are the concentrations of H2, I2, and HI after the system has achieved a state of equilibrium?

Kc = 50.5

[H2] = 0.002 M

[I2] = 0.007 M

[HI] = 0.026 M

7.  Kc for this reaction is 50.5. In what direction will the reaction proceed if the initial concentrations are: [H2] = 0.015 M; [I2] = 0.0012 M; [HI] = 0.025 M?

H2(g) + I2(g) ßà 2HI (g)

Q < K proceeds forward

8.  What changes in equilibrium occur at constant temperature if: N2(g) + O2(g) ßà 2NO(g)

  1. Partial pressure of N2(g) is increased à
  2. The pressure of NO(g) is decreased à
  3. The total pressure of the system is increased no change
  4. Total volume of the system is increased no change

9.  A solution has a pH of 5.6. Calculate H+ and OH- concentrations and pOH value.

[H+] = 2.5·10-6

[OH-] = 4.0·10-9

pOH = 8.4

10.  Calculate pOH and pH of a 0.02 M KOH solution.

pOH = 1.7

pH = 12.3

11.  At 1000 K, Kp = 1.85 for the reaction: SO2(g) + ½ O2 (g) ßà SO3 (g)

  1. What is the value of Kp for the reaction SO3 (g) ßà SO2(g) + ½ O2(g)?

0.541

  1. What is the value of Kp for the reaction 2 SO2(g) + O2 (g) ßà 2 SO3 (g)?

3.42

  1. What is the value of Kc for the reaction in part b?

280.8