Question

Using the bond energies below, calculate an estimate of δhrxn for the hypothetical gas phase reaction: nx3 + 3h2o => nh3 + 3hox do not enter units with your answer. bond be (kj/mol) n-x 263 o-h 464 n-h 389 o-x 229

Answer 1

ΔHrxn = 327

______NX3 + 3H2O → NH3 +_3HOX

Bonds: 3N-X__6O-H_3N-H_3O-H_3O-X

D:____263___464____389__464__229

The formula relating ΔHrxn and bond dissociation energies (D) is

ΔHrxn = Σ(Dreactants) – Σ(Dproducts)

Σ(Dreactants) = 3×263 + 6×464 = 789 + 2784 = 3573

Σ(Dproducts) = 3×389 + 3×464 + 3×229 = 1167 + 1392 + 687 = 3246

ΔHrxn = 3573 – 3246 = 327