Exercise 11 | Lewis Formulas

Calculate the change in enthalpy ΔH0 of the following reaction:

CH4 + 2 O2 → CO2 + 2 H2O

Is this an endothermic or exothermic reaction?


Data:

Bond energy (BE):

H-H = 436 kJ.mol-1

C-H = 413 kJ.mol-1

C-C = 347 kJ.mol-1

C=C = 607 kJ.mol-1

C-O = 358 kJ.mol-1

C=O = 805 kJ.mol-1

O-O = 204 kJ.mol-1

O=O = 498 kJ.mol-1

O-H = 464 kJ.mol-1

 

ΔH0 = 4 BE (C-H) + 2 BE (O=O) – 2 BE (C=O) – 4 BE (O-H) = -818 kJ.mol-1

ΔH0 < 0 ⇒ the reaction is exothermic.