Question

What is the relationship between enthalpy and entropy?

Answer 1

See below

Explanation:

Enthalpy (`H`) is defined as the amount of energy released or absorbed during a chemical reaction.

Entropy (`S`) defines the degree of randomness or disorder in a system.

Therefore, there is no direct relationship between entropy and enthalpy. However, the free energy (`G`) regroups both terms as:
`G=H-TS`

where at constant temperature, the change on free energy is defined as: `Delta G=DeltaH-TDeltaS`.

Therefore, the free energy expression provides a relationship between enthalpy and entropy.

Thus, for a system at equilibrium, `DeltaG=0`, and then we find that `DeltaS=(DeltaH)/T`.