AP Chemistry – Ch 15 & 16 Study Guide

  1. When the following reactions come to equilibrium, does the equilibrium mixture contain mostly reactants or mostly products?
  2. N2 (g) + O2 (g) ↔ 2NO (g) Kc = 1.5 × 10-10
  3. 2SO2 (g) + O2 (g) ↔ 2SO3 (g)Kp = 2.5 × 109
  1. If Kc = 0.042 for PCl3 (g) + Cl2 (g) ↔ PCl5 (g) at 500 K, what is the value of Kp at this temperature?
  1. The following equilibria were attained at 823K:

CoO (s) + H2 (g) ↔ Co (s) + H2O (g) Kc = 67

CoO (s) + CO (g) ↔ Co (s) + CO2 (g)Kc = 490

Based on these equilibria, calculate the equilibrium constant for H2 (g) + CO2 (g) ↔ CO (g) + H2O (g) at 823 K.

  1. A mixture of 0.30 mol of NO, 0.080 mol of H2, and 0.30mol of H2O is placed in a 1.0 L vessel at 300K. The following equilibrium is established

2NO (g) + 2H2 (g) ↔ N2 (g) + 2H2O (g)

At equilibrium [NO] = 0.062 M.

  1. Calculate the equilibrium concentrations of H2, N2, and H2O.
  2. Calculate Kc.
  1. A mixπture of 0.2000 mol of CO2, 0.1000 mol of H2, and 0.1600 mol of H2O is placed in a 2.000L vessel at 500K.

CO2 (g) + H2 (g) ↔ CO (g) + H2O (g)

  1. Calculate the initial partial pressures of CO2, H2, CO, and H2O.
  2. At equilibrium, PH2O = 3.51 atm. Calculate the equilibrium partial pressures of CO2, H2, and CO.
  3. Calculate Kp for the reaction.
  1. At 100C, Kc = 0.078 for the reaction

SO2Cl2 (g) ↔ SO2 (g) + Cl2 (g)

In an equilibrium mixture of the three gases, the concentrations of SO2Cl2 and SO2 are 0.108M and 0.052 M, respectively. What is the partial pressure of Cl2 in the equilibrium mixture?

  1. At 1285C, the equilibrium constant for the reaction Br2 (g) ↔ 2Br (g) is 1.04  10-3. A 0.200L vessel containing an equilibrium mixture of gases has 0.245 g of Br2 (g) in it. What is the mass of Br in the vessel?
  1. At 373K, Kp = 0.416 for the equilibrium

2NOBr (g) ↔ 2NO (g) + Br2 (g)

If the pressure of NOBr (g) and NO (g) are equal, what is the equilibrium pressure of Br2?

  1. How do the following changes affect the value of the equilibrium constant for a gas phase exothermic reaction:
  2. Removal of a reactant?
  3. Removal of a product?
  4. Decrease in volume?
  5. Decrease in temperature?
  6. Addition of a catalyst?
  1. Designate the Brønsted-Lowry acid, base, conjugate acid, and conjugate base.
  2. HCOOH (aq) + PO43- (aq) ↔ HCOO- (aq) + HPO42- (aq)
  3. O2- (aq) + H2O (l) ↔ OH- (aq) + OH- (aq)
  1. Which of the following is a stronger Brønsted-Lowry acid, HBrO or HBr?
  1. At the freezing point of water, Kw = 1.2  10-15. Calculate [H+] and [OH-] for a neutral solution at 0C.
  2. If NaOH is added to water, how does [H+] change? How does the pH change?
  1. Complete the chart below.

[H+] / [OH-] / pH / pOH / Acid or Base?
7.5 x 10-3
3.6 x 10-10
8.25
5.7
  1. Calculate the pH, pOH, and [OH-] of the following strong acid solutions:
  2. 8.5  10-4 M HBr.
  3. 1.52 g of HNO3 in 575 mL of solution.
  4. A solution formed by mixing 10.0 mL of 0.100 M HI with 20.0 mL of 0.200 M HCl.
  1. Lactic acid (CH3CH(OH)COOH) has one acidic hydrogen. A 0.10M solution of lactic acid has a pH of 2.44. Calculate Ka.
  1. A 0.100 M solution of chloroacetic acid (ClCH2COOH) is 11.0% ionized. Using this information, calculate [ClCH2COO-], [H+], [ClCH2COOH], and Ka for chloroacetic acid.
  1. Saccharin, a sugar substitute, is a weak acid with a pKa of 2.32 at 25C. It ionizes in aqueous solution as follows:

HNC7H4SO3 (aq) ↔ H+ (aq) + NC7H4SO3- (aq)

What is the pH of a 0.10 M solution of this substance?

  1. Calculate the % ionization of hydrazoic acid (HN3) in a 0.400 M solution. Ka is 1.9  10-5.
  2. Calculate the molar concentrations of OH- ion in a 0.075 M solution of ethylamine (C2H5NH2), Kb = 6.4  10-4. Calculate the pH of this solution.
  1. Although the acid dissociation constant for phenol (C6H5OH) is listed in Appendix D in your textbook, the base dissociation constant for the phenolate ion (C6H5O-) is not.
  2. Explain why it is not necessary to list both Ka and Kb for phenol and the phenolate ion.
  3. Calculate Kb for the phenolate ion.