Bong Enthalpy accuracy  [ENDORSED]

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Chew 2H
Posts: 34
Joined: Fri Sep 29, 2017 7:05 am

Bong Enthalpy accuracy

Postby Chew 2H » Wed Jan 17, 2018 4:01 pm

Why again are bond enthalpies the least accurate? In exams, do we always try to use Hess Law unless told otherwise?

Lisa Tang 1C
Posts: 62
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Re: Bond Enthalpy accuracy  [ENDORSED]

Postby Lisa Tang 1C » Wed Jan 17, 2018 4:16 pm

Bond enthalpies are the least accurate method of calculating reaction enthalpies because they are average values from many different molecules. Bond enthalpies are accurate for diatomic molecules, though.
The three methods are Hess's Law, bond enthalpies, and using standard enthalpies of formation, so I think you use the method that makes the most sense in the situation.

Julia Campbell 2F
Posts: 31
Joined: Sat Jul 22, 2017 3:00 am

Re: Bong Enthalpy accuracy

Postby Julia Campbell 2F » Wed Jan 17, 2018 8:46 pm

Use whatever information is given to you, but yes Hess's Law is more accurate.

Christina Bedrosian 1B
Posts: 33
Joined: Fri Sep 29, 2017 7:05 am

Re: Bong Enthalpy accuracy

Postby Christina Bedrosian 1B » Thu Jan 18, 2018 10:23 am

I think when we are given the question, there will be only one method that fits the question so I don't think you would have much of a choice to not use this method but it is just worth knowing that this method is the least accurate.

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