Calculating enthalpy of formation with resonance

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Kaitlin_Reeves_1C
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Joined: Wed Sep 21, 2016 2:59 pm

Calculating enthalpy of formation with resonance

Postby Kaitlin_Reeves_1C » Mon Jan 16, 2017 4:15 pm

For part C of #67 in the chapter 8 textbook problems, we are asked to calculate the enthalpy of formation for benzene (C6H6) without resonance. For part D, we are asked to calculate the enthalpy of formation for benzene with resonance. How do I factor resonance into the calculations?

Matt_Coopersmith_4H
Posts: 20
Joined: Wed Sep 21, 2016 2:57 pm

Re: Calculating enthalpy of formation with resonance

Postby Matt_Coopersmith_4H » Mon Jan 16, 2017 7:42 pm

The first step in this question would be to find the types of bonds present in the benzene ring with resonance, and without resonance.

For part C, there would be 3 C-C (single) bonds and 3 C--C (double) bonds, which you can look up.
However, for part D, resonance is included and thus there would be 6 Carbon Carbon bonds of resonance. A resonance depiction of bonds can be given with what looks like a double bond, but with the top bond (top line) being dotted. You will find this configuration with a different enthalpy value to finish solving the problem.

Hope this helps!


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