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 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 Horxn for the reaction:


ΔHorxn = Σ (bonds broken) Σ (bonds formed)