A solution contains 0.0330 M Pb2 (aq) and 0.0330 M Sr2 (aq). If we add SO42 - (aq), what will be the concentration of Pb2 (aq) when SrSO4 (s) begins to precipitate?

The Ksp of PbSO₄ = 2.53 * 10⁻⁷

for srSO₄→ 3.44 * 10⁻⁷

for srSO₄

srSO₄→ Sr²⁺ + SO₄⁻

Ksp = [sr²⁺] [SO₄⁻]

3.44 ˣ 10⁻⁷ = (0.0330M) [ SO₄⁻]

[SO₄⁻] = 8.1 ˣ 10⁻⁶M

foe Pb SO₄

PbSO₄ →Pb²⁺ + SO₄⁻

Ksp = [ Pb²⁺] [ SO₄⁻]

2.53 ˣ 10⁻⁸M

= [ Pb²⁺] (8.1 ˣ10⁻⁶M)

[Pb²⁺] = 2.75 ˣ 10⁻³M