Question

A mixture of formic acid and oxalic acid is heated with conc. `H_2SO_4` . The gas produced is collected and treated with `KOH` solution where the volume decreases by 1/6th. The molar ratio of two acids (formic acid/oxalic acid) in the original mixuture is:
(a) `4:1`
(b) `1:4`
(c) `2:1`
(d) `1:2`

Answer 1

Let `x` mol of `HCOOH` and y mole of `(COOH)_2`
`underset(x)HCOOHoverset(H_2SO_4)toH_2O+underset(x)CO`
`underset(y)(COOH)_2overset(H_2SO_4)toH_2O+underset(y)CO+underset(y)CO_2`
total mol of `(CO+CO_2)=x+2y`
Total mol of `CO_2=y`
Accordig to the question,
`(x+2y)xx(1)/(6)=y` `therefore(x)/(y)=4:1`
Alternatively
Mol fraction of `CO_2=(y)/(x+2y)=(1)/(6)`
`(x)/(y)=4:1`