Question

Derive how the free energy change is related to the total entropy change of a system.

Answer 1

The Gibbs free energy combines enthalpy and entropy in one value. It is the energy associated with a chemical reaction that can be useful. It is equivalent to subtraction of enthalpy from temperature and system entropy.

Free energy refers to the amount of energy available during a chemical reaction to do cellular work.

Gibbs free energy equation

$\Delta G\quad =\quad \Delta H-\quad T\Delta S\\ \\\Delta G\quad =\quad Gibbs\quad free\quad energy\\ \\T\quad =\quad Temperature\quad in\quad Kelvins\\ \\\Delta S\quad =\quad Entropy\quad change$

If $\Delta G\quad$ is negative, thus it is a forward reaction and is spontaneous.

If $\Delta G\quad$ is zero, the system is at equilibrium.

If $\Delta G\quad$ is positive, the reaction is spontaneous in the reverse direction.