Question

A hydrocarbon compound consisting solely of carbon and hydrogen is found $96$ % carbon by mass. Find the empirical formula of this compound.

• A. $C_{2}H$
• B. $C{H}_2$
• C. $C_{3}H$
• D. $C{H}_3$
• E. $C_{4}H$

Answer 1

The correct option is A $C_{2}H$

100 g of hydrocarbon contains 96 g C and 4 g H.
The atomic masses of C and H are 12 g/mol and 1 g/mol respectively.
Number of moles of C $=\frac{96}{12}=8$ moles.
Number of moles of H $=\frac{4}{1}=4$ moles.
The ratio of number of moles of C to the number of moles of H $=8:4=2:1$
The empirical formula of the compound is $C_{2}H$