Using the standard heats of formation that follow, calculate the standard enthalpy change for the following reaction. 2NH3(g) + 3N2O(g)4N2(g) + 3H2O(g)

Question

Using the standard heats of formation that follow, calculate the standard enthalpy change for the following reaction. 

2NH₃(g) + 3N₂O(g)4N₂(g) + 3H₂O(g)     H°_rxn =  kJ

Species	H°f (kJ/mol)
NH3(g)	-46.1
N2O(g)	82.1
H2O(g)	-241.8

Answer 1

ΔH°_rxn = (ΣΔH°_products) - (ΣΔH°_reactants)

= (n ΔH°_H2O) - (n ΔH°_NH3 + n ΔH°_N2O)

= (3 mol x -241.8 kJ/mol) - (2 mol x -46.1 kJ/mol + 3 mol x 82.1 kJ/mol)

= (-725.4 kJ) - (-92.2 kJ + 246.3 kJ)

= (-725.4 kJ) - (154.1 kJ)

= -879.5 kJ