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Entropy Criterion and Spontaneity || Chemistry || +2

Entropy Criterion and Spontaneity

Entropy Criterion and Spontaneity

In chemistry, it is a core concept in physical chemistry. Key Takeaways: Entropy Entropy is a measure of the randomness or disorder of a system. The value of entropy depends on the mass of a system. It is denoted by the letter S and has units of joules per kelvin. Entropy can have a positive or negative value. According to the second law of thermodynamics, the entropy of a system can only decrease if the entropy of another system increases.

A spontaneous process is the time-evolution of a system in which it releases free energy and it moves to a lower, more thermodynamically stable energy state. The sign convention for free energy change follows the general convention for thermodynamics measurements, in which a release of free energy from the system corresponds to a negative change in the free energy of the system and a positive change in the free energy of the surroundings.

let us consider a system which is at higher temperature ‘r’ than a total of its surrounding temperature ‘T2’. Let us consider q amount of heat is irreversibly supplied from the system to the surrounding. The change in entropy can be calculated as.

The decrease in entropy of a system

Entropy Criterion and Spontaneity

And, the increase in entropy of the surrounding

Entropy Criterion and Spontaneity

The total entropy change i.e. ∆S total can be given as:

Entropy Criterion and Spontaneity

Since T1 is greater than T2 so T1-T2 is always found to be positive and the process is a spontaneous process.

If ∆S total> 0, the process is spontaneous in a direction as described with the condition. If ∆S total= 0, the process is equilibrium in nature and if ∆S total<0, the process is non-spontaneous in a direction as described with the condition.
Therefore this is Entropy Criterion and Spontaneity.

If you liked our content Entropy Criterion and Spontaneity, then please don’t forget to check our other content Second Law of Thermodynamics

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