Question

Which of the following expressions represents the solubility product for Cu(OH)$_2$?

• A. $K_{sp} = [{Cu}^{2+}][{OH}^-]^2$
• B. $K_{sp} = [{Cu}^{2+}]^2[{OH}^-]$
• C. $K_{sp} = [{Cu}^{2+}]^2[{OH}^-]^2$
• D. $K_{sp} = [{Cu}^{2+}][{OH}^-]$

Hint:

Remember, for salts that dissociate into more than one hydroxide ion, the concentration of OH$^-$ is raised to the power of its stoichiometric coefficient.

Answer 1

The Correct Option is A

The solubility product, $K_{sp}$, is the product of the concentrations of the ions in their dissolved state, each raised to the power of its respective coefficient in the dissociation equation. For copper(II) hydroxide, Cu(OH)$_2$, the dissociation is given by: \[ {Cu(OH)}_2 \rightleftharpoons {Cu}^{2+} + 2 {OH}^- \] Thus, the expression for the solubility product is: \[ K_{sp} = [{Cu}^{2+}][{OH}^-]^2 \] Hence, the correct answer is (a).