## Chemistry: The Molecular Science (5th Edition)

Molar mass of PbS = $239.3\,g/mol$ Mass percent of Pb= $86.60\%$ Mass percent of S= $13.40\%$
Molar mass of PbS= Molar mass of Pb+ Molar mass of S $=207.2\,g/mol+ 32.065\,g/mol$ $= 239.3\,g/mol$ Mass percent of Pb=$\frac{207.2\,g}{239.265\,g}\times100\%$ $=86.60\%$ Mass percent of S= $\frac{32.065\,g}{239.265\,g}\times 100\%$ $=13.40\%$