Sign of the Gibbs for a reaction profile

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garrett_perozich
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Joined: Wed Sep 21, 2016 2:57 pm

Sign of the Gibbs for a reaction profile

Postby garrett_perozich » Sun Mar 05, 2017 5:07 pm

When drawing a reaction profile given the equation, for example, CH3CHCH2 + HBr, how do we know whether the final Gibbs free energy will be lower or higher than the initial? We were asked to do this twice on the homework for chapter 4, once for Gibbs, and the other for potential, and both times I assumed that the final energy was lower than the initial, but is that always the case? If not, then how exactly would I determine whether it is or isn't given no numerical data?

Eugenia Kwon 3O
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Joined: Wed Sep 21, 2016 2:59 pm

Re: Sign of the Gibbs for a reaction profile

Postby Eugenia Kwon 3O » Sun Mar 05, 2017 7:01 pm

In this case we were given a specific example of the reaction HBr and Propene which is defined to have products that are in lower energy than reactants. For now the organic textbook only went through three examples for each type of reaction (electrophilic addition, aromatic substitution, and the SN2) so I assume we memorize the reactions for now.

Chem_Mod
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Re: Sign of the Gibbs for a reaction profile

Postby Chem_Mod » Mon Mar 06, 2017 1:30 pm

You can assume these reactions are spontaneous so delta G will be negative.

Linh Ngau 1F
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Joined: Fri Jul 22, 2016 3:00 am

Re: Sign of the Gibbs for a reaction profile

Postby Linh Ngau 1F » Mon Mar 06, 2017 1:49 pm

Will the reactions we be given always be spontaneous? Or will there be instances where we get a reaction that is endergonic as opposed to exergonic; is this fair game for the final?


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