Bond Enthalpy Accuracy

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Shannon Asay 1C
Posts: 102
Joined: Fri Aug 09, 2019 12:16 am

Bond Enthalpy Accuracy

Postby Shannon Asay 1C » Fri Jan 24, 2020 2:32 pm

Why is using bond enthalpies the least accurate method for calculating delta H?

Alexis Webb 2B
Posts: 124
Joined: Thu Jul 11, 2019 12:15 am

Re: Bond Enthalpy Accuracy

Postby Alexis Webb 2B » Fri Jan 24, 2020 2:55 pm

I think it is because the bond enthalpies are calculated as averages from many different molecules, so they are not the most accurate.

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

Re: Bond Enthalpy Accuracy

Postby Ellen Amico 2L » Fri Jan 24, 2020 3:04 pm

Bond enthalpies are for breaking bonds in gases, so you need to add in the enthalpy of phases changes for reactants/products that are liquid or solid. Additionally, they're averages from many different molecules, which makes them less accurate. Using Hess's Law or the standard enthalpies would be a better method.

Sanjana Borle 2K
Posts: 111
Joined: Fri Aug 09, 2019 12:15 am

Re: Bond Enthalpy Accuracy

Postby Sanjana Borle 2K » Fri Jan 24, 2020 3:41 pm

Bond enthalpies are only accurate with diatomic molecules with atoms of the same type, otherwise it is not so accurate since the enthalpy is calculated using averages.

Asha Agarwal 1E
Posts: 51
Joined: Fri Aug 30, 2019 12:16 am

Re: Bond Enthalpy Accuracy

Postby Asha Agarwal 1E » Fri Jan 24, 2020 3:55 pm

Bond enthalpies of diatomic molecules are completely accurate, but for all other bonds formed the bond enthalpy given is an average of all different bonds of that nature that occurred instead of the actual value for that specific bond or reaction, so there is some error, making it the least accurate.

Leyna Dang 2H
Posts: 104
Joined: Thu Jul 25, 2019 12:17 am

Re: Bond Enthalpy Accuracy

Postby Leyna Dang 2H » Fri Jan 24, 2020 5:57 pm

I'm not sure but I think it has to do with the fact that the bond enthalpies of all molecules other than diatoms are averages. Since the averages are given and not the actual values, they aren't as accurate.

Daria MacAuslan 1H
Posts: 50
Joined: Sat Aug 17, 2019 12:16 am

Re: Bond Enthalpy Accuracy

Postby Daria MacAuslan 1H » Fri Jan 24, 2020 6:30 pm

The enthalpy of bonds is calculated by taking the averages of many different molecules, so you cant get a perfectly accurate and specific value for this. For diatomic molecules, however, it is accurate.


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