Question

How is Gibbs free energy related to enthalpy and entropy?

Answer 1

Gibbs free energy (G)

• Gibbs free energy is the energy associated with a chemical reaction that can do useful work.
• Mathematically, it is calculated by the formula

$\mathrm{G}=\mathrm{H}–\mathrm{TS}$

• Here, G= Gibbs free energy, H= Enthalpy, T= Temperature, S= Entropy
• At constant temperature

$\mathrm{\Delta G}=\mathrm{\Delta H}–\mathrm{T\Delta S}$

Where $∆\mathrm{G}$= Change in Gibbs free energy,

$∆\mathrm{H}$= Change in Enthalpy,

T= Temperature,

$∆\mathrm{S}$= Change in Entropy

Enthalpy (H)

• Enthalpy (H) is a measure of how much energy is released or absorbed during a chemical reaction.
• In an exothermic reaction, energy, in the form of heat, is released and the change in enthalpy is negative,$-\mathrm{H}$.
• In an endothermic reaction, heat is absorbed, and the change in enthalpy is positive,$+\mathrm{H}$.

Entropy(S)

• Entropy measures the amount of heat dispersed or transferred during a chemical process.
• Entropy also measures the randomness occurring in a system or surroundings during a process.
• The entropy of the system and surroundings are opposite to each other.
• The entropy of the universe is always increasing.

Gibbs’ energy is the energy available to initiate a chemical process under constant pressure and temperature.