An important step in the synthesis of nitric acid is the conversion of ammonia to nitric oxide. 4NH3(g) + 5O(g) 4NO(g) + 6HO(g) Calculate AHxn for this reaction. AHf [NH3(g)] = -45.9 kJ/mol; AHf [NO(g)] = 90.3 kJ/mol; AHf [HO(g)] = -241.8 kJ/mol -105.6 kJ O 906.0 kJ O 197.4 kJ O-197.4 kJ -906.0 kJ