### Gibbs Free Energy

Posted:

**Sun Feb 17, 2019 11:30 pm**Can someone explain what Gibbs Free Energy is? I understand the equations but I don't really know what it means conceptually.

Created by Dr. Laurence Lavelle

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

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=135&t=42381

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Posted: **Sun Feb 17, 2019 11:30 pm**

Can someone explain what Gibbs Free Energy is? I understand the equations but I don't really know what it means conceptually.

Posted: **Sun Feb 17, 2019 11:41 pm**

I am also confused, I recall the professor saying something about Gibbs Free Energy being leftover energy, but I just donâ€™t remember from what.

Posted: **Sun Feb 17, 2019 11:55 pm**

I think it describes the overall spontaneity of the system and whether it is achieved through the delta s or delta h.

Posted: **Mon Feb 18, 2019 4:12 pm**

To start understanding what our free energy means, we can look at the equation of delta G = delta H - Temp*(delta S).

Our delta H (enthalpy) value is in joules or kilojoules, and multiplying our entropy value times the temperature of the reaction will give us a value in joules as well. So, we can see that our Gibbs free energy is definitely in terms of energy.

Now we know we've derived an energy term, we can see conceptually that we're subtracting the entropy of the reaction (the energy that is the disorder or loss) from the enthalpy (the total heat of the reaction). This means that we're essentially subtracting the "lost" energy from the total, leaving us with an energy term that can be used for getting the "free energy" or the energy left to do work. That's what it means when use the term free energy, since it's a function to find just how much useful energy we have.

Our delta H (enthalpy) value is in joules or kilojoules, and multiplying our entropy value times the temperature of the reaction will give us a value in joules as well. So, we can see that our Gibbs free energy is definitely in terms of energy.

Now we know we've derived an energy term, we can see conceptually that we're subtracting the entropy of the reaction (the energy that is the disorder or loss) from the enthalpy (the total heat of the reaction). This means that we're essentially subtracting the "lost" energy from the total, leaving us with an energy term that can be used for getting the "free energy" or the energy left to do work. That's what it means when use the term free energy, since it's a function to find just how much useful energy we have.

Posted: **Mon Feb 18, 2019 4:40 pm**

Since gibbs free energy is a measure of spontaneity and based on delta h and delta s, if delta h is really low (such as an exothermic reaction) it is more likely to be spontaneous and if delta s is really high (more likely to become disordered) with a high temperature it is more likely to be spontaneous.

Posted: **Tue Feb 19, 2019 1:02 am**

Gibbs free energy is the energy available to do work. I think it means that this energy is able to be used up in a reaction and is not wasted as heat.