The 'heat of total cracking' of hydrocarbons `DeltaH_(TC)` is defined as `DeltaH` at `298.15 K` and `101.325 kPa` for the process below
`C_(n)H_(m) +(2n-(m)/(2))H_(2)(g) rarr nCH_(4)(g)`
Given that `DeltaH_(TC)` is `-65.2 kJ` for `C_(2)H_(6)` and `-87.4 kJ` for `C_(3)H_(8)`, calculate `DeltaH` for
`CH_(4)(g) +C_(3)H_(8)(g) rarr 2C_(2)H_(6)(g)`

Explanation

`DeltaH_(TC)` of `CH_(4)=0`
`CH_(4)(g)+C_(3)H_(8)(g)to2C_(2)H_(6)(g)`
`DeltaH=2DeltaH_(TC)(C_(2)H_(6))-DeltaH_(TC)(C_(3)H_(8))`
`=2(-65.2)-(-87.4)=-43kJ`