Hess Cycle Q

Calculate the average N-H bond energy in NH3(g) using the data below. ∆Hêf of NH3(g) = -46 kJ mol-1
Bond enthalpies: N≡N = 944; H-H = 436 kJ mol-1

How do you answer this and draw the Hess's cycle?

Reply 1

qwert7890

Original post by TarunSuprai01

What does enthalpy change of formation mean? It's when one mole of a compound is formed from its elements under standard conditions.
So the equation would be:

0.5 N₂ + 1.5 H₂ ----> 1 NH₃

Okay, so now the fact that bond enthalpy is mentioned in the question should give you a hint. Bond enthalpy refers to the diatomic molecules like N₂ and H₂ to be broken down into single atoms like simply N or simply H.

Does this give you a hint? How can you break the reactants on the left of the equation to use the bond enthalpies in the form of a Hess Cycle?