For the reaction Pb(NO3)2 (aq) + LiBr ...?

Question

PbBr2 precipitates out. Calculate the percent yield (%) if 11.061g of PbBr2 precipitates when 1.700L of 0.0500M Pb(NO3)2 (aq) and 1.260L of 0.0562M LiBr are mixed.

Answer 1

Pb(NO3)2 + 2LiBr -> PbBr2 + 2LiNO3

1.7*0.05 = 8.5 x 10^-2 mol of Pb(NO3)2

1.260 x 0.0562 = 7.08 x 10^-2 mol of LiBr

Thus 3.54 x 10^-2 mol of Pb(NO3)2 can react as LiBr is the limiting reagent.

Molar mass of PbBr2 = 208 + 2*80 = 368 g

Mass that should come = 368 x 3.54 x 10^-2 = 13.0272 g

Thus % yield = 11.061/13.0272 x 100 = 84.9 %