GRE Subject Test: Chemistry - Equilibrium Constant and Reaction Quotient

Which of the following is true regarding the solubility product constant, $\small K_{sp}$ , for a reaction in the form:

$aA_{(s)}\rightleftharpoons cC_{(aq)}+dD_{(aq)}$

The concentration of substance $\small A$ strongly influences the value of $\small K_{sp}$

As more of substance $\small A$ dissolves in the given solution, $\small K_{sp}$ increases

$\small K_{sp}$ represents the ratio of reactants to products as the reaction progresses

$K_{sp}=[C]^c[D]^d$

$\small K_{sp}$ has units of moles per liter

Explanation

To determine the solubility product constant, we only need the concentrations and coefficients of the ions. The effective concentration of any pure substance (solid, liquid, or gas) is equal to one by definition, so does not influence the value of $\small K_{sp}$ . The equation for the solubility product constant of this reaction is:

$K_{sp}=[C]^c[D]^d$

The units of the solubility product constant will depend on the coefficients of the products. $\small K_{sp}$ will be a constant for the reaction, and will not change as more solid dissolves or as the reaction progresses.

Equilibrium Constant and Reaction Quotient

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