Help! Mass calculation!!?

Question

A beaker containig Pb(NO3)2. dissolved in water. Than adds a solution of NaI, and a bright yellow precipitate is formed. Then contiues to add NaI until no further yellow precipitate is formed. The person filters the precipitate, dries it in an oven, and finds the mass of 1.43g.
Use a balanced chemical equation to determine what mass of lead nitrate Pb(NO3)2 was dissolved in the water in the beaker.

Answer 1

The ppt is PbI2.

Molar mass = 208 + 254 = 462

Thus no. of moles = 3.1x10^-3

Pb(NO3)2 + 2 NaI -> 2NaNO3 + PbI2

Molar mass of Pb(NO3)2 = 270

mass of Pb(NO3)2 = 0.837 g