Chemistry Homework: Calculate Enthelpy Change

[shawonna23]

1. Calculate the approximate enthalpy change for the combustion of methane:
CH4 + 2O2 ---> 2H20 + CO2

2. Homework Equations

CH4 + 2O2 ---> 2H20 + CO2

enthalpy= D(reactants) - D(products)

D= bond dissociation energies

Bond Dissociation energy (KJ/MOL)

C-C 350
C=C 611
C-H 410
C-O 350
C=O 732
O-O 180
O=O 498
H-O 460

3. The Attempt at a Solution

ENTHALPY= D(reactants)-D(products)
[1640+(2*498)]-[(2*920)-1464]= -668 kJ

 

[Borek]

[1640+(2*498)]-[(2*920)-1464]= -668 kJ

Why [(2*920)-1464]?

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