Reaction Profile Delta G

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Rachel Colbath 2G
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Joined: Fri Sep 25, 2015 3:00 am

Reaction Profile Delta G

Postby Rachel Colbath 2G » Sun Feb 28, 2016 10:55 pm

In a 2 step reaction, the reaction profile would have two transition states. In the process of figuring out which has a larger delta G, would you measure the difference between the top of both the first and the second transition states to the initial reaction delta G value? Or would you compare TS1 with the initial delta G level and compare TS 2 with the pseudo-equilibrium between TS1 and TS2? Which one do we pick and why?

Julia Spaczai 2G
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Joined: Fri Sep 25, 2015 3:00 am

Re: Reaction Profile Delta G

Postby Julia Spaczai 2G » Mon Feb 29, 2016 10:34 am

I believe that when you're trying to measure which transition state has a larger delta G, you would compare TS1 with the free energy of the reactants and then TS2 with the free energy of the intermediates, or the pseudo-equilibrium between TS1 and TS2. However, I'm not sure why this is the case either.

Chem_Mod
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Re: Reaction Profile Delta G

Postby Chem_Mod » Tue Mar 01, 2016 12:47 pm

This is incorrect. When measuring deltaG, always compare TS1 and TS2 to the energy of the reactants. It is determining activation energy where the energy of TS1 is compared to the energy of reactants and TS2 is compared to energy of intermediates.

Alli Foreman 2H
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Re: Reaction Profile Delta G

Postby Alli Foreman 2H » Tue Mar 01, 2016 4:27 pm

Does that mean that the graph on the top of page 157 in the orange book is incorrect?

Joyce Zhang 2D
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Re: Reaction Profile Delta G

Postby Joyce Zhang 2D » Sun Mar 05, 2017 4:55 pm

It's not wrong, it's just that we won't be using it in this course.

"Organic chemists often do this (use the other model) because it is more convinient to determine all difference with respect to the reactants...we will do the same from this point on"(157)


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