Given the three formation equations and their enthalpy values, calculate the enthalpy of the given reaction.
H2(g) + S(g) -->H2S(g) delta Hf = - 20.17 kj/mol
S(g) + O2(g) -->SO2(g) delta Hf = -296.8 kj/mol
H2(g) + 1/2O2(g) --> H2O(g) delta Hf = -285.8 kj/mol
H2S(g)+ O2(g)-->SO2(g)+ H2O(g) what is the delta H rxn = ?