Gibb's free energy gives the energy which is easily available in the system, it can be used to do work. But I wonder what is the origin of the Gibb's free energy? Can anyone explain at the molecular point of view? As in, say the electrons are in a random state of motion, so the collective energy they have at that point of time, can be used for work -- Or, it is that we cannot actually explain it like this, cuz afterall Gibb's free energy is explained from a a macroscopic point of view.
Origin of Gibb's free energy
- Thread starter TheClimber
- Start date
I don't know much about the Gibbs free energy
(which is why I didn't respond sooner)
However I have had a little poke about on the web <Wikipedia : Gibbs Free Energy >
One thing I notice is that in your post you indicate:
(which is why I didn't respond sooner)
However I have had a little poke about on the web <Wikipedia : Gibbs Free Energy >
One thing I notice is that in your post you indicate:
However, Wikipedia seems to indicate that it is the maximum energy theoretically available from the system.
Enthalpy is the maximum energy in a system. Gibbs free energy G = H - TS, where H is the enthalpy of the system. Due to an inherent disorder in the system (entropy, S) which cannot be converted to useful work, we have to subtract it from H
It was good you made this reply since it brings out your misunderstanding of the subject.
Woody told you true and was only trying to help.
I think he deserves thanks for that, don't you?
If heat content (enthalpy) is the maximum energy of a system I suggest you stand in front of a cannonball travelling at 200 Kilometers per hour and try to convince me that it has the same energy as a similar cannonball standing quietly by your left foot, but is at the same temperature as the travelling one.
A bit of mathematics for you.
yes, dG = dH - TdS with appropriate sign conventions.
BUT
T is always positive, and if dS is positive the process can be spontaneous.
If dH is negative (ie the process evolves heat) then dH and -Tds add and this makes dG more negative but greater in absolute value than dH.
This is the condition for a spontaneous process - that dG is negative (evolves energy)
As regards to your question, Gibbs free energy is no different than any other sort of energy.
It is a property of a body or system, a form of accounting, not a real entity like a cannonball. The caloric theory was discredited more than 250 years ago.
As an aside note that eneergy is not a conserved property under Einstinian relativity, the first law holds within any given frame but the energy sum will be different from frame to frame.