Standard Gibbs Free Energy of Activation

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Jenna_Hakel_2A
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Standard Gibbs Free Energy of Activation

Postby Jenna_Hakel_2A » Mon Mar 06, 2017 7:39 pm

In the textbook, it says that the standard gibbs free energy of activation for a second transition state is often drawn from the reactants until the second transition state rather than from the intermediates to the second transition state because it is more convenient to measure everything in terms of the free energy of the reactants. So, the lines indicating the change in standard gibbs free energy of activation for both the first and second transition states would be from the reactants. Which should be used on the quiz?

Chem_Mod
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Re: Standard Gibbs Free Energy of Activation

Postby Chem_Mod » Tue Mar 07, 2017 1:23 am

Generally, you would want to use the first transition state because it is the rate-limiting step. However, the question should specific which one to label.

Sylvia_Cai_3D
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Re: Standard Gibbs Free Energy of Activation

Postby Sylvia_Cai_3D » Thu Mar 09, 2017 1:20 am

You would draw from the reactants to wherever the transition state lies respectively on the two transition states when it is asking for Gibbs Free Energy. When it asks for potential energy, then for the first transition state you would draw from the reactants to the transition state then at the second transition state you would draw from the intermediates to the transition state (since it doesn't need as much energy to go to the second transition state from the energy level that the intermediates are at).

Chem_Mod
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Re: Standard Gibbs Free Energy of Activation

Postby Chem_Mod » Thu Mar 09, 2017 9:05 am

Physical chemists tend to draw it from the intermediates to transition state 2 whereas organic chemists tend to draw it from reactants to transition state 2. Either form will be accepted as long as it is properly labeled.

Caleb Lim 2M
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Re: Standard Gibbs Free Energy of Activation

Postby Caleb Lim 2M » Wed Mar 15, 2017 9:06 pm

When do we know when the transition state 1 activation energy is greater or less than transition state 2 activation energy? Also, how does it relate to K ? (Referring to the graphing portion of this topic)


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