Question

When aqueous solutions of K2SO4 and Pb(NO3)2 are combined, PbSO4 precipitates. Calculate the mass, in grams, of the PbSO4 produced when 2.46 mL of 0.132 M Pb(NO3)2 and 3.82 mL of 0.748 M K2SO4 are mixed. Calculate the mass to 3 significant figures.

Answer 1

reaction is

K₂SO_4(aq)  + Pb(NO₃)_2(aq)    2 KNO_3(aq) + PbSO_4(s)

calculate mole of reactant

no. of mole = Molarity volume of solution in liter

no. of mole of Pb(NO₃)₂  = 0.132 0.00246 = 0.00032472 mole

no. of mole of K₂SO₄  = 0.748 0.00382 = 0.00285736 mole

according to reaction Pb(NO₃)₂ and K₂SO₄ react in equimolar proportion therefore to react with 0.00285736 mole of K₂SO₄ require 0.00285736 mole of Pb(NO₃)₂ but Pb(NO₃)₂ given only 0.00032472 mole therefore Pb(NO₃)₂ is limiting reactant react completely.

According to reaction 1 mole of Pb(NO₃)₂ give 1 mole of PbSO₄ therefore 0.00032472 mole of Pb(NO₃)₂ give 0.00032472 mole of PbSO₄

molar mass of PbSO₄ = 303.26 gm / mole

then 0.00032472 mole of PbSO₄ = 303.26 0.00032472 = 0.0985 gm of PbSO₄

0.0985 gm of PbSO₄ precipitate.