Question

How much Pb(OH)2(in mg) can be added to 4.0liter of a 0.095 M KOH solution before precipitation starts? Ksp 4.2x10^-5

Answer 1

Ksp Pb(OH)2 = (Pb^2+)(OH^-)^2
Use 0.095M = (OH^-) and solve for Pb^2+.
That gives M Pb^2+ to start pptn.
M Pb^+2 = mols Pb^2+/L = mols Pb(OH)2/L.
M Pb^2+ from above and L (4.00) give mols. Then mols= grams/molar mass. You know molar mass and mols, solve for grams and convert to mg.

Answer 2

Awesome. Thank you so much!!!!!

Answer 3

which molar mass do you use? pb(OH)2 or pb2+?