Question

Calculate the molar solubility of CuSO. (Ksp = 8.1 x 10-16) a) in water b) in 0.10 M CUNO3(aq) solution

Answer 1

Q2. (a) Cu₂SO₃ (s) $\rightleftharpoons$ 2 Cu⁺ (aq) + SO₃^2- (aq)

Let molar solubility of Cu₂SO₃ = s

[Cu⁺] = 2s

[SO₃^2-] = s

K_sp Cu₂SO₃ = [Cu⁺]²[SO₃^2-]

8.1 x 10^-16 = (2s)² * (s)

8.1 x 10^-16 = 4s³

s = (8.1 x 10^-16 / 4)^1/3

s = 5.9 x 10^-6 M

molar solubility of Cu₂SO₃ = s = 5.9 x 10^-6 M

(b) Initial concentration of Cu⁺ = 0.10 M

[Cu⁺] = 2s + 0.10 M

[SO₃^2-] = s

K_sp Cu₂SO₃ = [Cu⁺]²[SO₃^2-]

8.1 x 10^-16 = (2s + 0.10 M)² * (s)

Let s << 0.10 M

8.1 x 10^-16 = (0.10 M)² * (s)

s = (8.1 x 10^-16) / (0.10 M)²

s = 8.1 x 10^-14 M

molar solubility of Cu₂SO₃ = s = 8.1 x 10^-14 M