Write the ksp expression for the sparingly soluble compound zinc cyanide, zn(cn)2.

Kps = [Zn²⁺].[CN⁻]²

Explanation:

Let's consider the solution of zinc cyanide.

Zn(CN)₂(s) ⇄ Zn²⁺(aq) + 2 CN⁻(aq)

The solubility product (Kps) is the equilibrium constant for this solution, that is, the product of the concentration of the products raised to their stoichiometric coefficients divided by the product of the concentration of the reactants raised to their stoichiometric coefficients. Only aqueous species are included in the expression of kps.

The Kps is:

Kps = [Zn²⁺].[CN⁻]²

the answer for sodium is 0.186

the answer for rubidium is 0.251