### Gibbs free energy and spontaneity

Posted:

**Sun Feb 11, 2018 3:04 pm**Is calculating G the only way to officially conclude spontaneity? Because based on the equation calculating merely entropy or enthalpy doesn't appear to be enough.

Created by Dr. Laurence Lavelle

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

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=135&t=27388

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Posted: **Sun Feb 11, 2018 3:04 pm**

Is calculating G the only way to officially conclude spontaneity? Because based on the equation calculating merely entropy or enthalpy doesn't appear to be enough.

Posted: **Sun Feb 11, 2018 3:07 pm**

Yeah, basically you need delta G to determine spontaneity.

Or you can use K to indirectly find the spontaneity at equilibrium.

Or you can use K to indirectly find the spontaneity at equilibrium.

Posted: **Sun Feb 11, 2018 3:08 pm**

A spontaneous process is one that increases the entropy of the universe, which we can calculate by taking the sum deltaS_{sys} + deltaS_{surr}.

So deltaG is not the ONLY way to determine thermodynamic favorability, but as it is often difficult to measure the change in entropies of system and surroundings, we make use of the changes in enthalpy and entropy of the system to calculate deltaG as an applicable method of determining spontaneity.

So deltaG is not the ONLY way to determine thermodynamic favorability, but as it is often difficult to measure the change in entropies of system and surroundings, we make use of the changes in enthalpy and entropy of the system to calculate deltaG as an applicable method of determining spontaneity.

Posted: **Sun Feb 11, 2018 3:14 pm**

Yes because entropy and enthalpy both affect the chance of spontaneity.