Question

A mixture of 2.3 g formic acid and 4.5 g oxalic acid is treated with conc. `H_(2)SO_(4)`. The evolved gaseous mixture is passed through KOH pellets. Weight (in g) of the remaining product at STP will be
A. `1.4`
B. `3.0`
C. `2.8`
D. `4.4`

Answer 1

Correct Answer - C
`HCOOH underset("Dehydrating Agent")overset(H_(2)SO_(4))(rarr) CO+H_(2)O (H_(2)O" abosrbed by "H_(2)SO_(4))`
`{:(("moles")_(i),=2.3/46=1/20,0,0),(("moles")_(f),0,1/20,1/20):}`
`H_(2)C_(2)O_(4) overset(H_(2)SO_(4))(rarr) CO+CO_(2)+H_(2)O [H_(2)O" absorbed by "H_(2)SO_(4)]`
`{:(("moles")_(i),=4.5/90=1/20,0,0,0),(("moles")_(f),0,1/20,1/20,1/20):}`
`CO_(2)` is absorbed by `KOH`
So the remaning product is only `CO`.
moles of `CO` formed from both reactions
`=1/20+1/20=1/10`
Left mass of `CO=` moles `xx` molar mass
`=1/10xx28`
`=2.8 g`