The molar solubility of manganese(II) carbonate is 4.2 × 10^-6^M. What is K_sp for this compound?

Question

Quizplus · Accepted Answer

Manganese(II) carbonate dissociates in water as follows:

MnCO3(s) ⇌ Mn2+(aq) + CO32-(aq)

The equilibrium expression for this reaction is:

Ksp = [Mn2+][CO32-]

We are given the molar solubility of manganese(II) carbonate, which is the number of moles of the compound that dissolve per liter of solution. Let x be the molar solubility of MnCO3. Then:

MnCO3(s) ⇌ Mn2+(aq) + CO32-(aq)
I         x           x

At equilibrium, the concentration of Mn2+ and CO32- ions is equal to x M. Therefore, we can substitute these values into the equilibrium expression and get:

Ksp = x^2

Substituting the given value of molar solubility into this equation gives:

Ksp = (4.2 × 10^-6)^2 = 1.764 × 10^-11

Because our answer must be expressed in scientific notation, we choose the closest value, D) 1.8 × 10^-11.

The Molar Solubility of Manganese(II) Carbonate Is 4