### Gibbs Free Energy vs Entropy

Posted:

**Thu Feb 21, 2019 11:06 am**What is the difference between Gibbs Free Energy and entropy and why is gibbs free energy so important??

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=135&t=42548

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Posted: **Thu Feb 21, 2019 11:06 am**

What is the difference between Gibbs Free Energy and entropy and why is gibbs free energy so important??

Posted: **Thu Feb 21, 2019 11:10 am**

Gibbs free energy (G) is the measure of the total amount of energy available to do work while entropy (S) is the measure of the disorder of the system. Gibbs free energy is calculated using enthalpy (H), temperature (T), and entropy (S) with the equation delta G = delta H - T(delta S).

Posted: **Thu Feb 21, 2019 11:19 am**

On that note, Gibbs free energy is important because it is used for looking at changes in a system with constant pressure and temperature. Most biomedical reactions occur at constant temperature and pressure, and G relates back to the spontaneity of a reaction. This is more convenient than looking at S to determine spontaneity.

Posted: **Thu Feb 21, 2019 11:32 am**

In addition to the answers above, Gibbs free energy also allows you to determine whether or not a reaction is likely to occur. Based on the ∆G°= ∆H°- T∆S, negative enthalpy and positive entropy will result to a negative Gibbs free energy, which favors the forward reaction. When enthalpy is positive and entropy is negative, Gibbs free energy be positive, which favors the reverse reaction. When Gibbs free energy is zero, the reaction is at equilibrium.

Posted: **Thu Feb 21, 2019 8:48 pm**

Gibbs free energy is the amount of energy available that can be used to preform work with entropy measures the disorder of the system. Gibbs free energy is so important because it allows us to determine if a reaction would proceed by itself to form products which is crucial under standard temp and pressure.