Question

An oxygen-containing organic compound was found to contain 52% carbon and 13% of hydrogen. Its vapour density is 23. The compound reacts with sodium metal to liberate hydrogen. A functional isomer of this compound is :

• A. ethanol
• B. ethanal
• C. methoxy methane
• D. methoxy ethane

Answer 1

The correct option is C methoxy methane

100 g of compound will contain $52$ g $C$, $13$ g $H$ and $100-52-13=35$ g of $O$.
The atomic masses of $C,H$ and $O$ are 12 g/mol, 1 g/mol and 16 g/mol respectively.

The number of moles of $C$ $=\frac{52}{12}=4.33$.

The number of moles of $H$ $=\frac{13}{1}=13$.

The number of moles of $O$ $=\frac{35}{16}=2.19$.

The mole ratio $C:H:O=4.33:13:2.19=2:6:1$
Hence, the empirical formula is $C_2{H}_{6}O$
The empirical formula mass is $2\left(12\right)+6\left(1\right)+16=46$ g/mol.
The vapour density is 23. The molecular formula mass is twice the vapour density. It is $2\times 23=46$
Hence, the empirical formula is equal to molecular formula.
The compound reacts with sodium metal to liberate hydrogen. Hence, the compound is ethanol.
$2C_2{H}_{5}OH+Na\to 2C_2{H}_{5}ONa+H_2$
A functional isomer of this compound is methoxy methane.