Question

The ksp of zinc carbonate (znco3 is 1.0 × 10–10. what is the solubility concentration of carbonate ions in a saturated solution at 25°c? 1.4 × 10–5m 7.1 × 10–6m 1.7 × 10–5m 1.0 × 10–5m

Answer 1

Ksp - solubility product constant is equivalent to equilibrium constant, except this constant is used to determine the solubility of ions of a solid in a solution. 
ksp is the product of the soluble ions in the compound. Higher the ksp value, higher the degree of solubility.
ZnCO₃ (s) ---> Zn²⁺ (aq) +  CO₃²⁻ (aq)
                         n            n
ksp = [Zn²⁺][CO₃²⁻]
In the equation equal amounts of ions Zn²⁺ and CO₃²⁻ ions are soluble. 
amount of ions soluble = n
ksp is therefore equal to;
ksp = n x n
ksp = n²
ksp = 1 * 10⁻¹⁰ M
therefore 
1 * 10⁻¹⁰ M = n²
n = 1 x 10⁻⁵ M
therefore concentration of CO₃²⁻ = 1 x 10⁻⁵ M

Answer 2

Answer is: 1.0 × 10–5m.
Chemical reaction: ZnCO₃(s) ⇄ Zn²⁺(aq) + CO₃²⁻(aq).
[Zn²⁺] = [CO₃²⁻] = x; equilibrium concentration of zinc cation and carbonate anion.
Ksp = [Zn²⁺] · [CO₃²⁻].
1·10⁻¹⁰ = x².
x = [CO₃²⁻] = √1·10⁻¹⁰.
[CO₃²⁻] = 1·10⁻⁵ M.