What is the maximum concentration of Ni²⁺ that can be added to a 0.00430 M solution of Na₂CO₃ before a precipitate will form? (Ksp for NiCO₃ is 1.30 × 10⁻⁷)

Answer 1

NiCO₃(s) <==> Ni²⁺(aq) + CO₃^2-(aq)

Ksp = 1.30x10^-7 = [Ni²⁺][CO₃^2-]

We have a common ion because we have a solution of Na₂CO₃ so CO₃^2- is the common ion.

[CO32-] = 0.00430 M

Ksp = 1.30x10^-7 = [Ni²⁺][0.00430]

[Ni²⁺] = 1.30x10^-7 / 0.00430

[Ni²⁺] = 3x10^-5 M