Why is using bond enthalpies the least accurate method of finding reaction enthalpies?

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John Huang 1G
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Why is using bond enthalpies the least accurate method of finding reaction enthalpies?

Postby John Huang 1G » Thu Jan 18, 2018 5:57 pm

I remember Lavelle discussing this, but I can't seem to recall why this is the case.

Cooper1C
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Re: Why is using bond enthalpies the least accurate method of finding reaction enthalpies?

Postby Cooper1C » Thu Jan 18, 2018 6:05 pm

Bond enthalpies are averages of many bonds.

Harsha 1J
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Re: Why is using bond enthalpies the least accurate method of finding reaction enthalpies?

Postby Harsha 1J » Thu Jan 18, 2018 8:25 pm

And I think the bond enthalpies are values under standard conditions, which might not always be the case.

Sarkis Sislyan 1D
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Re: Why is using bond enthalpies the least accurate method of finding reaction enthalpies?

Postby Sarkis Sislyan 1D » Thu Jan 18, 2018 9:00 pm

Only diatomic molecules have accurate bond enthalpy measurements, all other molecules' bond enthalpies are taken as averages

William Xu Dis 1D
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Re: Why is using bond enthalpies the least accurate method of finding reaction enthalpies?

Postby William Xu Dis 1D » Thu Jan 18, 2018 11:13 pm

While formation enthalpies are very precise, bond enthalpies are calculated as the average of many bonds. Even if you take the bond C-H, there are many different ways it can be formed into in different molecules.

Sarah Sharma 2J
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Re: Why is using bond enthalpies the least accurate method of finding reaction enthalpies?

Postby Sarah Sharma 2J » Fri Jan 19, 2018 10:26 am

Bond enthalpies are composed of multiple averages and therefore are an overall average. Whereas other values nad methods such as enthalpy of formation are much more accurate.


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