Chemistry 1410

Spring 2005

Practice Problems – Chapter 14

1. Consider the reduction of carbon dioxide by hydrogen to give water vapor and carbon monoxide at 420^oC.

H₂ (g) + CO₂ (g) D H₂O (g) + CO (g) K_c = 0.10

Suppose you have the following initial concentrations:

[H₂]_o = 2.50 M [CO₂]_o = 1.50 M [H₂O]_o = 2.00 M [CO]_o = 1.00 M

Calculate the equilibrium concentrations of all reactants and products.

Answer: [H₂]_eq = 3.09 M; [CO₂]_eq = 2.09 M; [H₂O]_eq = 1.41 M; [CO]_eq = 0.41 M

2. Acetic acid (HC₂H₃O₂) ionizes in water to form hydronium ion (H₃O⁺ ) and acetate ion (C₂H₃O₂^- ) . The equilibrium can be represented below:

HC₂H₃O₂ (aq) + H₂O (l) D H₃O⁺ (aq) + C₂H₃O₂^- (aq) K_c = 1.8 x 10^-5

What would be the equilibrium concentrations of acetic acid, hydronium ion, and acetate ion if the initial concentrations were:

[HC₂H₃O₂]_o = 0.00400 M [H₃O⁺]_o = 0.00 M [C₂H₃O₂^-]_o = 0.00 M

NOTE: The chemical structures involved here are:

[HC₂H₃O₂]_eq = 0.00374 M [H₃O⁺]_o = 0.000259 M [C₂H₃O₂^-]_o = 0.000259 M