Chapter 5, Problem 5.156QP

A mixture contained zinc sulfide, ZnS, and lead sulfide, PbS. A sample of the mixture weighing 6.12 g was reacted with an excess of hydrochloric acid. The reactions are

$\begin{array}{l}\text{ZnS}(s)+2\text{HCL}(aq)\to {\text{ZnCl}}_{\text{2}}(aq)+{\text{H}}_2\text{S(}g\text{)}\\ \text{PbS}(s)+2\text{HCL}(aq)\to {\text{PbCl}}_{\text{2}}(aq)+{\text{H}}_2\text{S(}g\text{)}\end{array}$

If the sample reacted completely and produced 1.049 L of hydrogen sulfide, H₂S, at 23°C and 762 mmHg, what were the percentages of ZnS and PbS in the mixture?