At a particular temperature, the solubility of In₂(SO₄)₃ in water is 0.0048 M.

Question

A) What is the value of Ksp?

B) If solid ln2(SO4)3 is added to the solution that already contains .200 M Na2SO4, what will the new solubility of the solid be?

C) If solid ln2(SO4)3 is added to the solution that already contains .150 M Na2SO4, what will the new solubility of the solid be?

Answer 1

(A) In₂(SO₄)₃(s) ==> 2 In³⁺(aq) + 3 SO₄^2-(aq)

Ksp = [In³⁺]²[SO₄^2-]³

[In³⁺] = 2 x 0.0048 M = 0.0096 M

[SO₄^2-] = 3 x 0.0048 M = 0.0144 M

Ksp = (0.0096)²(0.0144)³

Ksp = 2.75x10^-10

(B) Common ion effect:

[SO₄^2-] = 0.200 M

Ksp = [In³⁺]²[SO₄^2-]³ = (x)²(0.200)³

2.75x10^-10 = 0.008x²

x = 1.85x10^-4 M = [In³⁺]

molar solubility = 1/2 x 1.85x10^-4 M = 9.25x10^-5 M

(C) Common ion effect:

[SO₄^2-] = 0.200 M= 0.150 M

Repeat above calculation is (B) but use 0.150 in place of 0.200 M for [SO₄^2-]