An important step in the synthesis of nitric acid is the conversion of ammonia to nitric oxide. 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)
Calculate ΔH°_rxnfor this reaction.
ΔH°_f [NH₃(g) ] = −45.9 kJ/mol; ΔH°_f [NO(g) ] = 90.3 kJ/mol; ΔH°_f [H₂O(g) ] = −241.8 kJ/mol

Question

Quizplus · Accepted Answer

The correct answer is A because the ΔH°_rxn for this reaction is -906.0 kJ. This can be calculated using the following equation:ΔH°_rxn = ΣΔH°_f(products) - ΣΔH°_f(reactants)ΔH°_rxn = [4ΔH°_f(NO) + 6ΔH°_f(H₂O)] - [4ΔH°_f(NH₃) + 5ΔH°_f(O₂)]ΔH°_rxn = [4(90.3 kJ/mol) + 6(-241.8 kJ/mol)] - [4(-45.9 kJ/mol) + 5(0 kJ/mol)]ΔH°_rxn = -906.0 kJ

An Important Step in the Synthesis of Nitric Acid Is