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

$C_{4}H_{8}N_{2}O_{2}$
Empirical formula mass= $2(12.01\,g/mol)+4(1.0078\,g/mol)+(14.0067\,g/mol)+(15.999\,g/mol)$ $=58.057\,g/mol$ $\frac{\text{Molar mass}}{\text{Empirical formula mass}}=\frac{116.1\,g/mol}{58.057\,g/mol}=2$ Thus the subscripts in the empirical formula $C_{2}H_{4}NO$ need to be doubled to obtain the molecular formula, which is $C_{4}H_{8}N_{2}O_{2}$.