Final answer:
The reaction associated with the standard enthalpy of formation of NH3 (g) is N₂(g) + 3H₂(g) → 2NH3(g). The standard enthalpy of formation for this reaction is -92.2 kJ/mol.
Step-by-step explanation:
The reaction associated with the standard enthalpy of formation of NH3 (g) is:
N₂(g) + 3H₂(g) → 2NH3(g)
This reaction represents the formation of ammonia gas from nitrogen gas and hydrogen gas under standard conditions. The standard enthalpy of formation, ΔΗ, for this reaction is -92.2 kJ/mol. The negative value indicates that the reaction releases energy as heat.