0.16 g of methane was subjected to combustion at `27^(@)C` in a bomb calorimeter. The temperature of Calorimeter system (including water) was found to rise by `0.5^(@)C`. Calculate the heat of combustion of methane at
(i) constant volume (ii) constant pressure.
The thermal capacity of Calorimater system is `17.7" kJ K"^(-1)`. `(R=8.313" J mol"^(-1) K^(-1))`

Answer

(i) -885 kJ/mol (ii) -889.95 kJ/mol

Explanation

`CH_(4)+2O_(2) rarr CO_(2) +2H_(2)O`
Total energy relesed `=17.7xx0.5=8.85`
Energy released by one mole `CH_(4)=8.85/0.16 xx16=-885" kJ/mol"`
`DeltaH=DeltaU+Deltan_(g) RT rArr Deltan_(g) =-1 rArr DeltaH=-889.95" kJ/mol"`