A student measures the molar solubility of iron(II) carbonate, FeCO3, in a water solution to be 6.06 × 10-6 M. Based on her data, the solubility product constant for this compound is:. a. 8.90 × 10-27
b. 1.21 × 10-5
c. 3.67 × 10-11
d. 1.06 ×10-25
e. 8.17 × 10-27

The correct answer is c. 3.67 × 10⁻¹¹

Explanation:

The dissociation equilibrium and ICE table for FeCO₃ is the following:

        FeCO₃ (s) ⇄ Fe²⁺(aq) + CO₃²⁻(aq)

I                              0                0

C                             +s               +s

E                               s                 s

At equilibrium, the solubility product contant (Ksp) expression will be:

Ksp= [Fe²⁺] x [CO₃²⁻]= s x s = s²

Given: s= 6.06 x 10⁻⁶ M, we calculate Ksp as follows:

Ksp= s²= (6.06 x 10⁻⁶ M)²= 3.67 x 10⁻¹¹

Thus, from the given options the correct is c. 3.67 × 10⁻¹¹