Question

A. hydrocarbon contains 91.3%carbon by mass Find the empirical formula of hydrocarbon

Answer 1

"The empirical formula of hydrocarbon is $C_7 H_8$

Given:

The given percentage of carbon =91.3 %

To find:

Empirical formula

Solution:

Assume the mass of hydrocarbon is 100 gm.

The given percentage of carbon =91.3 % it is equal to 91.3 gm.

Mass of carbon = 91.3 gm

Mass of hydrogen = 100 -91.3 = 8.7 gm

Let's calculate moles of each element in hydrocarbon.

Number of moles of carbon=  $\frac {\text (Given mass)}{ \text (Molar mass)}$

$= \frac { 91.3 } { 12 } = 7.6 \text { moles } \cong 7$

Number of moles of Hydrogen$= \frac {8.7}{1}= 8.7 \text moles \cong 8$

Therefore, the empirical formula of hydrocarbon is $C_7 H_8$"