Question about Change in Gibb's Free Energy

[John Huang 1G]

If the change in Gibb's Free Energy (Delta G) for a spontaneous process represents the energy that is free to do useful work, then what does G (Gibb's Free Energy) represent?

[Masih Tazhibi 2I]

A big trend in thermodynamics is that it is hard to conceptualize and analyze these concepts in and of themselves, as some quantity. It is much more useful to analyze concepts like enthalpy, entropy, and Gibbs free energy as relative quantities, where you look at changes with respect to differing conditions, or with respect to the reaction taking place. The reason we focus on changes in Gibbs free energy, is because it tells us about the difference in energy states of the reactants and products, and thus which side of the reaction is favored. I would say G without the delta represents what the energy state of each side of the reaction is, and delta G represents the change in energy and whether energy will be output or input to drive the reaction to completion.

[Juanyi Tan 2K]

Just want to add on: enthalpy, entropy, and Gibbs free energy are all state functions, which means they are not dependent on path taken to obtain the current state. Therefore, it is more meaningful to focus on the change between different states.

[Nora Sharp 1C]

I believe deltaG can be used to represent the total amount of energy that is released or absorbed into or by a system during a chemical reaction. This energy released can be used to perform different functions, hence deltaG representing the amount of energy free to do work. For example, if we said ATP hydrolysis releases -7.3 kcal/mol of energy, we are saying that deltaG for the ATP reaction is -7.3 kcal/mol, and this released energy can be used to perform different tasks. When deltaG is positive, a system gains energy that it can release later and use to do work through different chemical reactions.

[Peter Dis1G]

I think it is the energy associated with a chemical reaction that can be used to do work.