Answer:
Hrxn = -241.82 kJ
Explanation:
2H2(g) + O2(g) --> 2H2O(g) Hrxn = -483.64 kJ ............. (i)
The equation for formation of 1 mol of H2O is given as;
H2(g) + 1/2O2(g) --> H2O(g) ................. (ii)
Eqn (ii) is obtained by dividing eqn (i) by 2
That means the heat of reaction for eqn (ii) is given as;
Hrxn = -483.64 kJ / 2
Hrxn = -241.82 kJ
