Positive Gibbs Free Energy






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megansardina2G
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Joined: Fri Sep 28, 2018 12:23 am
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Positive Gibbs Free Energy

Postby megansardina2G » Sun Feb 17, 2019 4:06 pm

How are reactions that have a positive ∆G carried out, as they are not spontaneous? (Especially in biological systems)

anthony_trieu2L
Posts: 60
Joined: Fri Sep 28, 2018 12:29 am

Re: Positive Gibbs Free Energy

Postby anthony_trieu2L » Sun Feb 17, 2019 4:33 pm

Reactions with a positive Gibbs free energy are usually carried out with accompaniment of another reaction. This is called a coupled reaction, and it allows the overall process to occur. An example is ATP hydrolysis, in which ATP is used to carry out the main reaction.

Sarah Zhao 4C
Posts: 64
Joined: Fri Sep 28, 2018 12:28 am

Re: Positive Gibbs Free Energy

Postby Sarah Zhao 4C » Sun Feb 17, 2019 4:46 pm

Non-spontaneous does not mean that it cannot happen. It rather means that it requires an input of energy to happen.

GavinAleshire1L
Posts: 29
Joined: Fri Sep 28, 2018 12:21 am

Re: Positive Gibbs Free Energy

Postby GavinAleshire1L » Sun Feb 17, 2019 4:47 pm

Like stated above, reactions with positive delta G usually involve coupling with ATP hydrolysis in order to carry out an anabolic reaction where the reactants form a higher energy product. These reactions are called endergonic. Another example of a reaction like this is photosynthesis which utilizes light energy instead of ATP to build glucose.


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