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26/09/2021 12:20 pm
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Given that:
(i) ΔH°f of N2O is 82 kJ mol-1
(ii) Bond energies of N ≡ N, N = N, O = O and N = O are 946, 418, 498 and 607 kJ mol-1 respectively,
The resonance energy of N2O is :
(a) -88kJ
(b) -66kJ
(c) -62kJ
(d) -44kJ
1 Answer
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26/09/2021 12:27 pm
Correct answer: (a) -88kJ
Explanation:
N2(g) + 1/2O2 → N2O(g)
N ≡ N(g) + 1/2(O = O) → N = \(\overset{+}N\) = O(g)
ΔH°f = [Energy required for breaking of bonds]–[Energy released for forming of bonds]
= (ΔHN≡N + 1/2ΔHO=O - (ΔHN≡N + ΔHO=O))
= (946 + 1/2 x 498) - (418 + 607)
= 170 kJ mol-1
Resonance energy = 82 - 170
= -88 kJ mol-1