Problem: Calculate the enthalpy of formation of ammonia from the following bond energy data:(N−N) bond =398 kJmol−1(H−H) bond =435 kJmol −1and (N≡N) bond =945.36 kJmol−1

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For this problem, we have to calculate the enthalpy of reaction (ΔH) of the formation of ammonia

N2 (g) + 3 H2 (g) → 2 NH3 (l) 

Recall that the change of enthalpy for a chemical reaction (ΔH) can be calculated using bond energies:

H = ΣBEreactants - ΣBEproducts


To determine the enthalpy of reaction, we need to first see what bonds are present in the reactants and the products.

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Problem Details

Calculate the enthalpy of formation of ammonia from the following bond energy data:
(N−N) bond =398 kJmol−1

(H−H) bond =435 kJmol −1

and (N≡N) bond =945.36 kJmol−1

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