Solution: Given the following reactionsH2O (l) →H2O (g)                    ΔH = 44.01 kJ2H2 (g) + O2 (g) → 2H2O (g)  ΔH = -483.64 kJthe enthalpy for the decomposition of liquid water into gaseous hydrogeand oxy

We’re being asked to determine the enthalpy change (ΔH_rxn) for the chemical reaction:

2 H₂O (l) → 2 H₂ (g) + O₂ (g) 

We can use Hess’s Law to determine the enthalpy change of the overall reaction from the given reactions:

1. H₂O (l) →H₂O (g)                                                         ΔH₁ = 44.01 kJ

2. 2H₂ (g) + O₂ (g) → 2H₂O (g)                                        ΔH₂ = - 483.64 kJ

We now need to find a combination of reactions that when added up, gives us the overall reaction.