8.73 Help (Bond Enthalpy)

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Joanna Pham - 2D
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Joined: Fri Apr 06, 2018 11:04 am

8.73 Help (Bond Enthalpy)

Postby Joanna Pham - 2D » Sun Feb 10, 2019 2:16 pm

For part a, the questions asks us to find the reaction enthalpy for 3C2H2 (g) -> C6H6 (g).

In the solutions manual, it says 6 moles of the C-C bonds are formed in the reaction. Where did they get 6 moles from? When I drew out the Lewis structure of C6H6, which came out to be a carbon ring with 6 hydrogens attached, I only see that 3
C-C bonds were formed. How did the manual arrive at 3?

Julia Lung 1I
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Joined: Fri Jun 23, 2017 11:39 am

Re: 8.73 Help (Bond Enthalpy)

Postby Julia Lung 1I » Sun Feb 10, 2019 2:20 pm

The solution only calculated the C-C bonds so there would be 3 mol of the CC triple bond broken and 6 mol of the C-C formed from the benzene ring.

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Joined: Fri Sep 28, 2018 12:28 am

Re: 8.73 Help (Bond Enthalpy)

Postby ryanhon2H » Sun Feb 10, 2019 2:24 pm

For bond enthalpies, the C-C and C=C bonds of benzene are counted the same. So since benzene has 3 single carbon bonds and 3 double carbon bonds, it is a total of 6 C-C/C=C bonds formed.

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