Enthalpy Change and Bond Energies

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1. Dec 27, 2015

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
6C-H bonds= 410 x 6 = 2460 kJ/mol
3C-C bonds
H of formation= +53.3 kJ/mol
H of atomisation = +717 kJ/mol
H-H = 436 kJ/mol

as H of formation is 53.3, can't I just do:
2460+3x=53.3?
But then I am not using a lot of the values provided and the answer in not in the options.

2. Dec 27, 2015

Bystander

You have to make a "good faith" effort.

3. Dec 27, 2015

Actually, I don't know what to do at all. I know that I have make a Hess's cycle so that I can form equations. But I can't figure out the Hess's cycle here.

4. Dec 27, 2015

Bystander

What is Hess's cycle?

5. Dec 27, 2015

The total enthalpy change is the same for all the routes the reaction can take to produce the product.

6. Dec 27, 2015

Bystander

Correct. What route are you taking?

7. Dec 27, 2015

Let the C-C bond energy be x
(3*-717) + (-436*3) + (410*6) + 3x = 53.3
-2151-1308+2460+3x=53.3
-999+3x=53.3
3x=1052.3
x=350.767
approx. 351 kJ/mol

But the answer should be 315kJ/mol.

8. Dec 27, 2015

Bystander

Were you to use conventional notation, you might be more successful.

9. Dec 28, 2015