Question

Use the Ksp values to calculate the molar solubility of each of the following compounds in pure water.

Part A MX (Ksp = 9.20×10−11) Express your answer in moles per liter.

Part B Ag2CrO4 (Ksp = 1.12×10−12)

Part C Ca(OH)2 (Ksp = 4.68×10−6) Express your answer in moles per liter.

Answer 1

A)

The salt dissolves as:

MX <----> M+ + X-

   s s

Ksp = [M+][X-]

9.2*10^-11=(s)*(s)

9.2*10^-11= 1(s)^2

s = 9.592*10^-6 M

Answer: 9.59*10^-6 moles/L

B)

The salt dissolves as:

Ag2CrO4 <----> 2 Ag+ + CrO42-

   2s s

Ksp = [Ag+]^2[CrO42-]

1.12*10^-12=(2s)^2*(s)

1.12*10^-12= 4(s)^3

s = 6.542*10^-5 M

Answer: 6.54*10^-5 moles/L

C)

The salt dissolves as:

Ca(OH)2 <----> Ca2+ + 2 OH-

   s 2s

Ksp = [Ca2+][OH-]^2

4.68*10^-6=(s)*(2s)^2

4.68*10^-6= 4(s)^3

s = 1.054*10^-2 M

Answer: 1.05*10^-2 moles/L