The molar solubility of C a ( O H ) 2 C a ( O H ) 2 was experimentally determined to be 0.019 M. Based on this value, what is the K s p K s p of C a ( O H ) 2 C a ( O H ) 2 ?

Ksp = 2.74 x 10⁻⁵

Explanation:

The solubility equilibrium for Ca(OH)₂ is the following:

  Ca(OH)₂(s) ⇄ Ca²⁺(aq) + 2 OH⁻(aq)

I                          0                0

C                       + s               + 2s

E                        s                   2s

According to the ICE table, the expression for the solubility product constant (Kps) is:

Ksp = [Ca²⁺] x ([OH⁻])² = s x (2s)² = 4s³

Then, we calculate Ksp from the solubility value (s):

s = 0.019 M

⇒ Ksp = 4s³ = 4 x (0.019)³ = 2.74 x 10⁻⁵