A mixture of `H_2C_2O_4` and `HCOOH` is heated with conc `H_2SO_4`. The gas produced is collected and on treatment with KOH solution, the volume of the gas decreases by `(1)/(6)` calculate the molar ratio of the two acids in the original mixture.

Explanation

Suppose no. of moles of formic acid is x and that of oxalic acid is y. Then
`underset(x)("mole")overset(Conc.)underset(H_(2)SO_(4))rarrH_(2)O_(4)(l)+underset("x mole")(CO(g))`
`underset(" y mole"){:(" "COOH),(" |"),(" "COOH):}rarr underset("y mole")(CO(g))+underset("y mole")(CO_(2)(g))+H_(2)O(l)`
Total no. of moles of gaseous product `=x+2y`
As only `CO_(2)` is absorbed by KOH, therefore, fraction of `CO_(2)=(y)/(x+2y)=(1)/(6)" (Given)"`
`"or "6y=x+2y or 4y=x or (x)/(y)=(4)/(1)`
Hence, molar ratio of `HCOOH` to `(COOH)_(2)` is `4:1`