Question

A compound contains $14$ percent hydrogen and $86$ percent carbon and what information you can give about that compound?

• A. It is a hydrocarbon
• B. Its empirical formula is $C{H}_2$
• C. Its molecular formula is $C_2{H}_4$
• D. Its molar mass is $28g/mol$
• E. It contains a triple bond

Answer 1

Answer: (B)

Its empirical formula is $C{H}_2$

Analysis by mass of a certain compound shows that it contains 14 % hydrogen and 86 % carbon. On the basis of the given data it can properly be made about the compound that its empirical formula is $C{H}_2$ .

100 g of compound will contain 14 g of hydrogen and 86 g of carbon.
The atomic masses of hydrogen and carbon are 1 g/mol and 12 g/mol respectively.
The number of moles is equal to the ratio of mass to atomic mass.
Number of moles of C$=\frac{86}{12}=7.17$ moles.
The number of moles of H $=\frac{14}{1}=14$.
The ratio of the number of moles of C to the number of moles of hydrogen is $\frac{7.17}{14}\simeq \frac{1}{2}$.
Hence, the empirical formula of the compound is $C{H}_2$.