(adsbygoogle = window.adsbygoogle || []).push({}); 69. Calculate the Ksp for each of the salts whose solubility is listed below.

a) CaSO4 = 3.3 x 10-3 mol/L

b) MgF2 = 2.7 x 10-3 mol/L

Answers:

a) Solution

1. Write the dissociation reaction and the Ksp expression for the equilibrium reaction. Thus,

CaSO4(s) <---> Ca2+ (aq) + SO42- (aq)

Ksp = [Ca2+][SO42-]

2. Calculate the concentrations of the ions at equilibrium from the stoichiometric information provided in the equilibrium equation. The equation shows that 1 mol of CaSO4 produces 1 mol of Ca2+ and 1 mol of SO42- at equilibrium. Therefore,

[Ca2+] = 3.3 x 10-3 mol/L

[ SO42-] = 3.3 x 10-3 mol/L

3. Substitute the concentrations into the Ksp expression:

Ksp = (3.3 x 10-3)( 3.3 x 10-3)

= 1.2 x 10-5

b) MgF2 <---> Mg2+ (aq) + F22+ (aq)

Ksp = [Mg2+][F22+]

[Mg2+] = 2.7 x 10-3

[F22+] = 2.7 x 10-3

Ksp = (2.7 x 10-3)(2.7 x 10-3)

= 7.3 x 10-6

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Calculating Ksp of salt (answer check)

**Physics Forums | Science Articles, Homework Help, Discussion**