Hydrogen sulfide, H2S, is a poisonous gas with the odor of rotten eggs. The reaction for the formation of H2S from the elements is: H2(g) + 1/8 S8(rhombic) → H2S(g) 1.4.1 Use Hess’s law to obtain the enthalpy change for this reaction from the following enthalpy changes: H2S(g) + 3/2 O2(g) → H2O(g) + SO2(g); ΔH = - 518 kJ H2(g) + 1/2 O2(g) → H2O(g); ΔH = - 242 kJ 1/8 S8(rhombic) + O2(g) → SO2(g); ΔH = - 297 kJ