Calcium carbonate is used to form exoskeletons. It has a solubility-product constant of 5.0 * 10^-⁹. What is the molar concentration of calcium ions in a saturated solution of calcium carbonate?

Question

Quizplus · Accepted Answer

The solubility-product constant (Ksp) of calcium carbonate is given as:

Ksp = [Ca2+][CO32-]

Since calcium carbonate is a sparingly soluble salt, the concentration of calcium ions in a saturated solution is expected to be low.

Let x be the molar concentration of calcium ions in a saturated solution of calcium carbonate. Then, the concentration of carbonate ions is also x because the salt dissolves in a 1:1 ratio.

Substituting these values in the expression for Ksp, we get:

Ksp = x^2

5.0 x 10^-9 = x^2

x = 7.1 x 10^-5 M

Therefore, the molar concentration of calcium ions in a saturated solution of calcium carbonate is 7.1 x 10^-5 M, which is closest to option B.

Calcium Carbonate Is Used to Form Exoskeletons