Calculating bond enthalpies

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Ellen Amico 2L
Posts: 101
Joined: Thu Sep 19, 2019 12:16 am

Calculating bond enthalpies

Postby Ellen Amico 2L » Sat Feb 08, 2020 3:20 pm

When finding calculating bond enthalpies, do we account if there's multiple of the same bond? For example, for CH3 do we multiply the C-H bond enthalpy by 3?
Also, will calculating bond enthalpies be a skill we really need to know for the test since it's the least accurate method of calculating enthalpy of a reaction?

Kate Swertfager
Posts: 50
Joined: Wed Sep 18, 2019 12:17 am

Re: Calculating bond enthalpies

Postby Kate Swertfager » Sat Feb 08, 2020 3:28 pm

Only multiply it by 3 if all three of the bonds are broken. IF two of the bonds are broken, then multiply that bond breakage by 2.

Kate Swertfager
Posts: 50
Joined: Wed Sep 18, 2019 12:17 am

Re: Calculating bond enthalpies

Postby Kate Swertfager » Sat Feb 08, 2020 3:29 pm

Its on the practice midterm so I would study up on it. There is a really good example in the text book.

Rory Simpson 2F
Posts: 106
Joined: Fri Aug 09, 2019 12:17 am

Re: Calculating bond enthalpies

Postby Rory Simpson 2F » Sat Feb 08, 2020 3:37 pm

The number that you multiply by depends on the number of bonds broken or formed. For example, if there are 2 C-C bonds broken in the reaction, then take the bond enthalpy for a C-C bond and multiply it by 2. You should probably know how to do it because certain problems might only give you the bond enthalpies for a reaction when you need to calculate delta H.

Jasmine Fendi 1D
Posts: 108
Joined: Sat Aug 24, 2019 12:15 am

Re: Calculating bond enthalpies

Postby Jasmine Fendi 1D » Sat Feb 08, 2020 4:03 pm

Multiply by 3 if all three bonds are being broken. It definitely will not be a big part of the test, but since we did go over it in lecture we are expected to know how to do it.


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