Question

If 100 ml of some pb(no3)2 solution is mixed with 100 ml of 6.50 x 10−2 m nacl solution, what is the maximum concentration of the pb(no3)2 solution added if no solid pbcl2 forms? (assume ksp = 2.00 x 10−5 m at this temperature.) enter the concentration in m.

Answer 1

Suppose X (in unit M) be the required maximum concentration of the Pb(NO₃)₂ solution added after mixing with 100 ml of 6.5 x 10⁻² M NaCl, the Pb²⁺ concentration is:
[Pb²⁺] = (X*100) / 200 = 0.5 X
The concentration of Cl⁻ is:
[Cl⁻] = (100 / 200) * (6.5 x 10⁻² M) = 0.0325 M
So:
Ksp = 2.00 x 10⁻⁵ = [Pb²⁺] [Cl⁻]² = (0.5X) * (0.0325)²
X = (2.00 x 10⁻⁵) / (5.28 x 10⁻⁴) = 0.038 M