CHM 2045C Module Seven Sample Exam

Module 7 Part I: Heat of Reaction from Bond Energies

Methane burns in oxygen to produce heat for homes by the following reaction:

CH₄ + 2 O₂ è CO₂ + 2 H₂O

If the average bond energies in kJ/mol are:

O-O 146

O=O 498

O-H 463

C-C 346

C-H 413

C-O 358

C=O 745

H-H 436

Calculate ∆H^o_rxn for the reaction:

ΔH^o_rxn = Σ (bonds broken) – Σ (bonds formed)