Negative Delta G






Moderators: Chem_Mod, Chem_Admin

Helen Mejia 1I
Posts: 67
Joined: Fri Sep 28, 2018 12:24 am

Negative Delta G

Postby Helen Mejia 1I » Mon Feb 18, 2019 10:53 pm

What are some conditions that allow delta G to be negative?

jessicahe4Elavelle
Posts: 61
Joined: Fri Sep 28, 2018 12:27 am
Been upvoted: 1 time

Re: Negative Delta G

Postby jessicahe4Elavelle » Mon Feb 18, 2019 11:00 pm

the formula for is delta G = delta H - T delta S. So if:
- delta H is positive and delta S is negative, delta G will definitely be positive
- delta H is negative and delta S is positive, delta G will definitely be negative

RachelCheung1A
Posts: 30
Joined: Fri Sep 28, 2018 12:19 am

Re: Negative Delta G

Postby RachelCheung1A » Mon Feb 18, 2019 11:08 pm

When delta H is negative and delta S is positive, it will definitely be negative delta G.
A large negative delta H and a small negative delta at a low temperature can possibly result in a negative delta G

Carine Tamamian 2B
Posts: 61
Joined: Fri Sep 28, 2018 12:23 am

Re: Negative Delta G

Postby Carine Tamamian 2B » Tue Feb 19, 2019 12:54 am

This graph will help better visualize the concept!
Attachments
figure-06-03-03.jpg

Sophie Roberts 1E
Posts: 61
Joined: Fri Sep 28, 2018 12:17 am

Re: Negative Delta G

Postby Sophie Roberts 1E » Tue Feb 19, 2019 9:24 am

Also it is important to remember when Delta G is negative the reaction is spontaneous!
When it is positive it is non spontaneous.

JadeSebti1L
Posts: 35
Joined: Fri Sep 28, 2018 12:19 am

Re: Negative Delta G

Postby JadeSebti1L » Tue Feb 19, 2019 10:21 am

Reactions with a negative delta G are very spontaneous, and therefore highly favorable! The more favorable a reaction is, the more it will proceed towards the products. That means that K is rather large at equilibrium because the ratio of products is high compared to reactants.

Milena Aragon 2B
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

Re: Negative Delta G

Postby Milena Aragon 2B » Tue Feb 19, 2019 11:01 am

The only circumstance in which delta G cannot be negative(for the forward rxn) regardless of temp. is if delta H is positive and delta S is negative.

Danielle_Gallandt3I
Posts: 70
Joined: Fri Sep 28, 2018 12:24 am

Re: Negative Delta G

Postby Danielle_Gallandt3I » Tue Feb 19, 2019 12:08 pm

It is important to remember that for the majority of problems you will actually have to use the delta G equation to determine the spontaneity of the reaction, because if if delta H is positive, the combination of the (negative) entropy and the temp must be large enough to overcome the enthalpy value. This means that at different temperatures delta G can change, which makes it important to calculate delta G for every scenario.


Return to “Gibbs Free Energy Concepts and Calculations”

Who is online

Users browsing this forum: No registered users and 2 guests