The energy change due to the reaction
`2Na(s) +CI_(2) (g) rarr2Na CI(s)` is `-826kJ`
The consumption of 1 mo1 of `CI_(2)` gas contracts the system by `22.4L` at 1 atm What is the enthalphy change of the reaction .

Explanation

`W = P DeltaV = 1atm xx 22.4 L = 22.4 L atm`
`= 22.4 L atm xx 101.3J`
`= 2.27 xx 10^(3) = 2.27 kJ`
The work done on the system is to be subtracted form the energy change to get enthalpy change,
`DeltaH = DeltaU +P DeltaV`
`=- 826 kJ + (-2.27 kJ) =- 828.27 kJ`