Question

For each of the following equilibria, write the equilibrium constant expression for Kc.

1. BaSO4(s) <---->Ba2+(aq) + SO42-(aq)

2. CH3COOH (aq) + H2O (l) <--->CH3COO- (aq) + H3O+ (aq)

Answer 1

1. Kc = [Ba2+][SO42-]

2. Kc = [CH3COO-][H3O+]/[CH3COOH]

Step-by-step explanation:

The equilibrium constant expression for Kc is the product of the concentrations of the products raised to their stoichiometric coefficients divided by the product of the concentrations of the reactants raised to their stoichiometric coefficients.

1. For the first equilibrium, BaSO4(s) <---->Ba2+(aq) + SO42-(aq), the equilibrium constant expression for Kc is: Kc = [Ba2+][SO42-].

2. For the second equilibrium, CH3COOH (aq) + H2O (l) <—>CH3COO- (aq) + H3O+ (aq), the equilibrium constant expression for Kc is: Kc = [CH3COO-][H3O+]/[CH3COOH].

Note that the concentration of water is not included in the expression because it is a pure liquid and its concentration is considered constant.

Answer 2

Equilibria are chemical reactions that happen with a change in the concentration of the reactants or products. If the forward reaction is favored, a greater concentration of the product will be formed than the reactant(s), and the reaction is said to be favored. If the reverse reaction is favored, a greater concentration of the reactant(s) will be formed and thus the reaction is said to be favored. An equilibrium constant (constant K), is a number that describes the ratio of products to reactants at an equilibrium. K is also referred to as the equilibrium coefficient.