## Energy Free to do Useful Work

$\Delta G^{\circ}= \Delta H^{\circ} - T \Delta S^{\circ}$

$\Delta G^{\circ}= -RT\ln K$

$\Delta G^{\circ}= \sum \Delta G_{f}^{\circ}(products) - \sum \Delta G_{f}^{\circ}(reactants)$

Ava Harvey 2B
Posts: 54
Joined: Fri Sep 29, 2017 7:04 am

### Energy Free to do Useful Work

So I understand that the change in Gibbs Free Energy, G, for a spontaneous process represents the energy that is free to do useful work. However, I was a bit confused on this concept because technically not all of the energy can be readily available to do work and will not necessarily be used to do work. Not sure if that makes sense, but if someone doesn’t mind trying to explain that concept, that would be great! Thanks so much!

Cyianna 2F
Posts: 34
Joined: Wed Nov 16, 2016 3:04 am

### Re: Energy Free to do Useful Work

Gibbs free energy is the energy that's left at the end of a reaction. This energy is still considered "useful work" because it's all the available energy that can be used for a specific purpose. Take the process of cellular respiration for example. By using oxygen and glucose, we can create ATP and CO2. In order for this to occur, many reactions use the free energy available from the products of a previous reaction. So in the long run, gibbs free energy is still energy available for use, regardless of how much is used.

Diego Zavala 2I
Posts: 65
Joined: Fri Sep 29, 2017 7:07 am
Been upvoted: 1 time

### Re: Energy Free to do Useful Work

Gibbs free energy measures the theoretical/maximum amount of work that a rxn could still do based on its "free" energy, however, because it is impossible for a reaction to be completely isolated, the "real" work that can be done will be less. I hope this clarifies the concept somewhat