Consider the reaction for the formation of aluminum oxide from aluminum and oxygen. 4Al(s)+3O2(g)⟶2Al2O3(s) ΔH1 Express the enthalpy of the following reaction, ΔH2, in terms of ΔH1. 2Al2O3(s)⟶4Al(s)+3O2(g) ΔH2 ΔH2= Express the enthalpy of the following reaction, ΔH3, in terms of ΔH1. 12Al(s)+9O2(g)⟶6Al2O3(s) ΔH3 ΔH3= Express the enthalpy of the following reaction, ΔH4, in terms of ΔH1 2Al(s)+3/2O2(g)⟶Al2O3(s)ΔH4 ΔH4=