Calculate the standard enthaly of formation of Methane. Given that the standard enthalpy of combustion of Methane, carbon and Hydrogen are -893.3kJ, -3.93kJ and -285.8kJ respectively.

Explanation

Required equation:
`C(S)+2H_(2)(g)toCH_(4)(g)DeltaH=?` ……1
`C(S)+O_(2)(g)toCO_(2)(g)DeltaH=-393.5kJ`………2
`H_(2)(g)+1//2O_(2)(g)toH_(2)O(l)DeltaH=-285.8kJ`………….3
`CH_(4)(g)+2O_(2)(g)toCO_(2)(g)+2H_(2)O(l)DeltaH=-890.3kJ`………….4
Eqn. 2 `xx1`, Eq. `3xx2` reverse Eqn 4 add
`2H_(2)(g)+O_(2)g to 2H_(2)O(l)DeltaH=-571.6kJ`
`CO_(2)(g)+2H_(2)O(l)toCH_(4)(g)+2O_(2)(g)DeltaH=+890.3kJ`
`C(S)+2H_(2)(g)toCH_(4)(g)DeltaH=-74.8kJ`