Enthalpy calculated from Bonds vs Enthalpy of formation

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Joshua Hughes 1L
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Enthalpy calculated from Bonds vs Enthalpy of formation

Postby Joshua Hughes 1L » Sun Jan 28, 2018 2:59 pm

I remember a question that was like why would there be a difference in the enthalpy calculated from bond enthalpies and the enthalpy of formations. Why is there a difference and which is more accurate? Would the bond enthalpies be more inaccurate because its just an average and can vary a lot due to conditions?

Tiffany Cao 1D
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Re: Enthalpy calculated from Bonds vs Enthalpy of formation

Postby Tiffany Cao 1D » Sun Jan 28, 2018 3:03 pm

Calculating enthalpies using bond enthalpy is the least accurate method since this method uses the average bond enthalpies. Because of this, bond enthalpies are not specific to certain molecules.

Sarah Wax 1G
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Re: Enthalpy calculated from Bonds vs Enthalpy of formation

Postby Sarah Wax 1G » Sun Jan 28, 2018 3:12 pm

Exactly. Using enthalpies of formation are a lot more accurate because it's the exact energy needed to form one mole of a substance. Bond enthalpies merely use averages of the exact energy needed to break/form a bond.

Phi Phi Do 2E
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Re: Enthalpy calculated from Bonds vs Enthalpy of formation

Postby Phi Phi Do 2E » Sat Feb 03, 2018 9:34 pm

This is because you are adding the average enthalpies within the bonds. Therefore, when you add up the total enthalpies, it is slightly inaccurate.


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