Using the following thermochemical data:
2 FeCl3(s) + 3 H2O(l)  Fe2O3(s) + 6 HCl(g) ΔH°r = +278.4 kJ
2 Fe(s) + 3 Cl2(g)  2 FeCl3(s) ΔH°r = –799.0 kJ
4 HCl(g) + O2(g)  2 Cl2(g) + 2 H2O(l) ΔH°r = –202.4 kJ
calculate ΔH° for the following reaction:
4 Fe(s) + 3 O2(g) → 2 Fe2O3(s) ΔH°rxn = ?