Bond Enthalpy Accuracy

[Shannon Asay 1C]

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

[Alexis Webb 2B]

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]

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]

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]

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]

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]

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.