Name: Gibbs Free Energy, EMF and Equilibrium Constant
Uploaded: 2019-07-19
Duration: 6 min 15 s
Description: There are various thermodynamic parameters that are to be considered while studying the working of an electrochemical cell. Let's learn about them here!

Question

Explain the spontaneity of a reaction in terms of enthalpy change, entropy change and Gibb's energy change.

Accepted Answer

A spontaneous process is an irreversible process, and it could only be reversed by some external agents. The entropy of any system is defined as the degree of randomness in it.

Generally, total entropy change is the essential parameter which defines the spontaneity of any process. Since most of the chemical reactions fall under the category of a closed system and open system; we can say there is a change in enthalpy too along with the change in entropy. Since, change in enthalpy also increases or decreases the randomness by affecting the molecular motions, entropy change alone cannot account for the spontaneity of such a process. Therefore, for explaining the spontaneity of a process we use the Gibbs energy change. Gibbs’ energy is a state function and an extensive property. The general expression for Gibbs energy change at constant temperature is expressed as :

${ΔG}_{sys} = {ΔH}_{sys} - {TΔS}_{sys}$

Thus, it can be inferred that any process is spontaneous if the change in Gibbs energy of the system is less than zero or else the process is not spontaneous.

Explain the spontaneity of a reaction in terms of enthalpy change, entropy change and Gibb's energy change.

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