`1.0`litre sample of a mixture of `CH_(4)` and `O_(2)` measured at `25^(@)C` and `740 ` torr, was allowed to react at constant pressure in a calorimeter, together with its contents had a heat capacity of `1260 cal K^(-1)`. The complete combustion of `CH_(4)` to `CO_(2)` and water caused a temperature rise in calorimeter of `0.667K`. Calculate mole `%` of `CH_(4)` in the original mixture. Heat of combustion of `CH_(4)` is `-210.8 kcal. `

Answer

`9.82" mol"% CH_(4)`

Explanation

Total energy released `=1260xx0.667=840.42 cal`
Moles of `CH_(4) =(840.42)/(215.10^(3)) =3.9xx10^(-13)`
Calculate V of `CH_(4)` By applying `PV=nRT`
`V=0.098246 L`
`%` moles of `CH_(4)=(0.098246)/(1) xx100=9.82 %`