Question

The concentration of Pb+2 in a sample of wastewater is to be determined by using gravimetric analysis. To a 100.0-mL sample of the wastewater is added an excess of sodium carbonate, forming the insoluable lead(II)carbonate (267.2092 g/mol) according to the balanced equation given below. The solid lead(II)carbonate is dried, and its mass is measured to be 0.6885 g. What was the concentration of Pb+2 in the original wastewater sample ?

Pb+2(aq)+Na2CO3(aq)->PbCO3(s)+2Na+(aq)

Answer 1

mass Pb = mass PbCO3 x (atomic mass Pb/molar mass PbCO3) = ?
(Pb^2+) = mass Pb^2+/0.1L = ? in moles/L