A solution contains 0.142 g of dissolved lead. How many moles of sodium chloride must be added to the solution to completely precipitate all of the dissolved lead?

Answer 1

balance the equation:
2NaCl(aq) + Pb >>>PbCl2 + Na+(aq)
so two moles of sodium chloride for each mole of Pb.
how many moles of Pb do you have?

Answer 2

Pb^2+(aq) + 2Cl^-*aq) ==> PbCl2(s)
mols Pb^2+ = grams/atomic mass = ?
mols NaCl must be twice mols Pb.