Question

The ksp of cobalt(ii) carbonate, coco3, is 1.0 × 10-10. calculate the solubility of this compound in g/l.

Answer 1

when Cobalt carbonate dissolves in water it dissociates as follows;
CoCO₃ --> Co²⁺ + CO₃²⁻
if the molar solubility of CoCO₃ is x then solubility of Co²⁺ is x and CO³⁻ is x as well.
Molar solubility is the number of moles of solute that are dissolved in 1 L of solution.
the formula for solubility product constant - ksp is as follows
ksp = [Co²⁺][CO₃²⁻]
ksp = x²
ksp = 1.0 x 10⁻¹⁰
x² = 1.0 x 10⁻¹⁰
x = 1.0 x 10⁻⁵
therefore molar solubility of CoCO₃ is 1.0 x 10⁻⁵M
molar mass of CoCO₃ is 119 g/mol
therefore solubility of CoCO₃ is 119 g/mol x 1.0 x 10⁻⁵ mol/L = 1.19 x 10⁻³ g/L