Question

The molecular mass of a compound having empirical formula $C_2{H}_{5}O$ is $90$. The molecular formula of the compound is :

• A. $C_6{H}_{15}{O}_3$
• B. $C_4{H}_{10}{O}_2$
• C. $C_2{H}_{5}O$
• D. $C_3{H}_6{O}_3$

Answer 1

The correct option is B $C_4{H}_{10}{O}_2$

The empirical formula is $C_2{H}_{5}O$ and empirical weight $=12\times 2+5\times 16=45$ g.
$n=\frac{\text{Molecular weight}}{\text{Empirical weight}}=\frac{90}{45}=2$
Therefore, the molecular formula is $C_4{H}_{10}{O}_2$.