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  Horxn for the reaction:

 

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