Answer
Empirical formula $C_5H_7N$
Molecular formula: $C_{10}H_{14}N_2$
Work Step by Step
Atomic weights (g/mol): $C: 12.011,\ H: 1.008,\ N: 14.007$
In 100.0 g:
C: $74.0\ g \div 12.011 = 6.16\ mol$
H: $8.65\ g\div 1.008 = 8.58\ mol$
N: $17.35\ g\div14.007=1.24\ mol$
Normalizing by the smallest amount of moles:
C: $6.16/1.24= 4.97$
H: $8.58/1.24= 6.92$
N: $1.24/1.24= 1.00$
Empirical formula $C_5H_7N$
Empirical formula's molar mass: $M_u=81.12\ g/mol$
$M/M_u=2.0$
Molecular formula: $C_{10}H_{14}N_2$
