CHEM-142
HW#3
Spring 2021
NAME:______________________________
1. If the value of the equilibrium constant, Kc, for the following reaction is 5 x 105 at 298 K,
what is the value of Kp at 298 K?
2 CO (g) + O2 (g) ⇌ 2 CO2 (g)
2. If the equilibrium constant Kc for reaction: 2 NO (g) + O2 (g) ⇌ 2 NO2 (g)
is 5 x 1012, what is the value of the equilibrium constant of each of the following reactions at the
same temperature?
a) NO (g) + ½ O2 (g) ⇌ NO2 (g)
b) 2 NO2 (g) ⇌ 2 NO (g) + O2 (g)
c) NO2 (g) ⇌ NO (g) + ½ O2 (g)
3. How is an equilibrium constant different from a reaction quotient?
4. In which direction will the following hypothetical reaction proceed to reach equilibrium under
the conditions given?
A (g) + B (g) ⇌ C (g) Kp = 1.00 at 300 K
PA = PC = 1.0 atm, PB = 0.50 atm
1
5. Write the Kc expression for the following reaction:
2 HCl (aq) + CaCO3 (s) ⇌ CaCl2 (aq) + H2O (l) + CO2 (g)
6. At 25 °C water reacts with dichlorine monoxide to form hypochlorous acid by the reaction
shown below. If a reaction is started with 0.060 M H2O and 0.023 M Cl2O, what are the
concentrations of the reactants and products at equilibrium?
H2O (g) + Cl2O (g) ⇌ 2 HOCl (g)
Kc = 9.0 x 10-2
2
7. How will the changes listed affect the position of the following equilibrium?
2 NO2 (g) ⇌ NO (g) + NO3 (g)
a) The concentration of NO is increased.
b) The concentration of NO2 is increased.
c) The volume of the system is allowed to expand.
8. Identify the acids and bases in the following reactions:
a) NH3 (aq) + H2PO4- (aq) ⇌ NH4+ (aq) + HPO42- (aq)
b) ClO- (aq) + H2O (l) ⇌ HClO (aq) + OH- (aq)
c) (CH3)3COH (aq) + H3O+ (aq) ⇌ (CH3)3COH2+ (aq) + H2O (l)
9. Calculate the pH and pOH of the solutions with the following hydrogen ion or hydroxide ion
concentrations. Indicate whether the solutions are acidic, basic, or neutral.
a) [H+] = 3.39 x 10-9 M
b) [OH-] = 6.37 x 10-2 M
3