Question

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

Answer 1

Kps = [Zn²⁺].[CN⁻]²

Step-by-step 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

Answer 2

The Ksp expression for Zn(CN)2 is written as follows

write the equation for dissociation

that is,
zN(CN)2 ------> Zn 2+(aq) + 2CN-(aq)


ksp is therefore = (Zn2+)( CN-)^2

CN- is raised to a power of two since there are two CN- ion in the equation above