The standard enthalpy change for the following reaction is 484 kJ at 298 K. 2 H2O(g) 2 H2(g) + O2(g) ΔH° = 484 kJ

Question

What is the standard enthalpy change for this reaction at 298 K?

H2(g) + 1/2 O2(g)  H2O(g)

Answer 1

The heat of formation reaction is the reaction that you are given reversed and halved.

You do the same thing to the ΔH_rxn as you do to the reaction statement. (Note reversing is multiplying by a negative)

Good luck.