Given: 4 NO2(g) + O2(g) → 2 N2O5(g) ΔH° = -110.2 kJ find ΔH° for N2O5(g) → 2 NO2(g) + 1/2 O2(g).

Answer 1

The equation in question is simply 1/2 of the reverse reaction of the equation provided.

To find the ∆Hº of this equation, divide the ∆Hº of the original equation by 2 and change the sign.