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Postby AtreyiMitra2L » Wed Jan 10, 2018 9:34 pm

In this question, we are supposed to use bond enthalpies to estimate the reaction enthalpy for 3C2H2(g)-->C6H6(g). In the solutions manual, it says that only 6 C H bonds are formed (where the bond is between a single and double). It seems to me that 4 C - H bonds are formed as well. Can someone please explain this to me?

Britney Alvey 1B
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Re: 8.73a

Postby Britney Alvey 1B » Wed Jan 10, 2018 10:21 pm

In this reaction, the C-H bonds are already formed in the C2H2 moleules. Each C2H2 molecule will look like H-C-C-H with the C-C being a triple bond. When the reaction happens, the triple bonds between the carbons are broken and the only new bonds formed are going to be between the carbons since the hydrogen are already bonded.

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