Question

A mixture of formic acid and oxalic acid is heated with conc. `H_(2)SO_(4)`. The gas producted is collected and treated with `KOH` solution, whereby the volume decrease by `1//6th`. The molar ratio of the two acids (formic acid/oxalic acid) is
A. `4:1`
B. `1:4`
C. `2:1`
D. `1:2`

Answer 1

Correct Answer - A
Let `x` mol of `HCOOH` and `y` mol of `COOH)_(2)`.
`underset(x)(HCOOH) overset(H_(2)SO_(4))rarr H_(2) + underset(x)(CO)`
`underset(x)((COOH)_(2)) overset(H_(2)SO_(4))rarr H_(2)O + underset(x)(CO) + underset(y)(CO_(2))`
Total moles of `(CO + CO_(2)) = x + 2y`
Total moles of `CO_(2) = y`
According to the question:
`(x + 2y) xx (1)/(6) = y`
`:. (x)/(y) = 4:1`
Alternatively:
Mole fraction of `CO_(2) = (y)/(x + 2y) = (1)/(6)`
`:. (x)/(y) = 4:1`