Problem 87P

Calculate the molar solubility of MgCO3.

Solution 87P:

Consider the equation

MgCO3.(s) ⇆ Mg2+(aq) + CO32-(aq)

Let us consider the solubility of MgCO3.(s) is “ S” mol/L.

Thus,

Solubility product = [Mg2+(aq)][ CO32-(aq)]

Ksp = [Mg2+(aq)][ CO32-(aq)] ------(1)

We know

Solubility product Ksp for MgCO3.is 6.82 x 10-6

Therefore, from equation (1)

6.82 x 10-6 = S. S

S2 = 6.82 x 10-6

= (6.82 x 10-6 )½ = 2.61 x 10-3 M

Thus, the molar solubility of MgCO3.is 2.61 x 10-3 M.