Question

3. If equal amounts of 0,010 M K2SO4 and ).10 M Pb(NO3)2 solutions are mixed, will a precipitate form? Ksp of PbSO4=1.8x10-8​

Answer 1

Answer: PbSO₄ is precipitated when an equal amount of 0.010 M K₂SO₄ and 0.10 M Pb(NO₃)₂ solutions are mixed.

Explanation:

Given that,

Molarity of K₂SO₄ = 0.010M

Molarity of Pb(NO₃)₂= 0.10M

Ksp of PbSO₄ = 1.8×10⁻8

ions in solution,

K₂SO₄(aq) (0.010M)⇒ 2K⁺(0.020M) + SO₄²⁻(0.010M)

Pb(NO₃)₂(aq)(0.10M)⇒ Pb²⁺(0.10M) + 2NO₃⁻(0.20M)

Reaction is, K₂SO₄+ Pb(NO₃)₂ ⇒ PbSO₄ + 2KNO₃

The volume will be double when we add an equal amount of K₂SO₄ and Pb(NO₃)₂.

Then the new molarity is,

Pb²⁺   $\frac{0.1M}{2}$= 0.050 M Pb²⁺

SO₄²⁻ $\frac{0.010M}{2}$ = 0.0050M SO₄²⁻

Q= 0.050×0.0050=2.5×10⁻4

Ksp= [Pb²⁺] [SO₄²⁻] = 1.8×10⁻8

Q>Ksp So, PbSO₄ will precipitate.