## what exactly is free energy?

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

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

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

cristiancampana 2H
Posts: 32
Joined: Fri Sep 29, 2017 7:07 am

### what exactly is free energy?

I'm not sure what free energy is, can someone explain it please ( as in Gibbs free energy)

Minie 1G
Posts: 63
Joined: Fri Sep 29, 2017 7:04 am

### Re: what exactly is free energy?

Free energy is like all the energy in the universe available to be released or consumed through reactions taking place. The Gibbs free energy is a measure of "usable" energy in the system. Basically how much energy you have available to do work.

So when we have deltaG, we are looking at the change in free energy as we progress through a reaction. A negative deltaG would release energy into the surroundings while a reaction with a positive deltaG takes energy to happen. Usually we refer to deltaG of a certain reaction. You can also consider deltaG of the entire universe, if you deem that to be your system.

mendozayael_2H
Posts: 31
Joined: Fri Sep 29, 2017 7:06 am

### Re: what exactly is free energy?

Gibbs free energy is the energy in a process that can be used to do work in the system. It can tell whether the enthalpy, temperature, and entropy (properties of a reaction) are favorable for a reaction to occur. Remember ΔG = ΔH - TΔS, (change in enthalpy - temperature * change in entropy).

aaron tang 2K
Posts: 49
Joined: Thu Jul 27, 2017 3:01 am

### Re: what exactly is free energy?

Gibbs free energy is basically the free energy in a process available to do work. An important relationship to consider is ΔG = ΔH - TΔS, which, if you know the signs of the unknowns, you can determine the sign of ΔG and hence predict if a reaction is favorable or not.

Cynthia Bui 2H
Posts: 30
Joined: Fri Sep 29, 2017 7:05 am

### Re: what exactly is free energy?

Like everyone's said, it's the energy available to do work. So when it change in G is negative, the reaction is spontaneous because that means there was enough energy to complete the reaction after accounting for changes in entropy.

Jessica Nunez 1I
Posts: 58
Joined: Thu Jul 13, 2017 3:00 am

### Re: what exactly is free energy?

In addition, if ΔG is negative, then it means that the reactants have more energy than the products which will allow the reaction to move forward (occurs spontaneously). If ΔG is positive, then it means that the reactants have less energy than the products, which will require an input of energy (does not occur spontaneously).