1.7 PHYSICAL SIGNIFICANCE OF ENTROPY- ENTROPY AS A MEASURE OF DISORD- B.SC 2ND YEAR

RITIK BHOLA

The physical significance of entropy can be well understood by an examinatiion of various processes which take place with an increase of entropy. On studying these processes, it has been founded that those processes which are accompained by anet increase of entropy also show an incresed randomness.

Consider, for example, the melting of a solid which is accompained by a net increase of entropy . In this case , at the same time there is an increase in th erandom ness of the atoms, ions or molecules .This is because, in the solids, the ions, atoms or molecules are supposed to have fixed positions and in the molten state, they become more free to move.

The evaporation of aliquid alsoi involves in entropoy as well as disorder

Similarly all spontaneous process like flow of heat from a hot end to a cold end of a conductor , transference of molecules of a solute from a more concentrated to a less concentrated solution, flow of electricity from a poin tat a higher potential to a point at a lower potential are all accompained by a net increased of entropy as well as an increase of randomness or disorder.it

follows from above examples that an increase in the entropy is also accompained by an increase in the disorder of the system.

Therefore entropoy is regarded as a measure of the disorder of the system.

Analogy from daily life The concept of entropy and randomness can be better understood by considering the following exmples in our daily life.

Consider the working of a college, when the different classes are being held in different rooms . The randomness or disorder is minimum. But when the bells goes, the students change their own classrooms and get mixed up for 2 – 3 minutes. For these 2 3 minutes, the randomness (or disorder) and hence, the entropy of the college increases .After 2 or 3 minutes, when the students again occupying different rooms, the randomness (or disorder ) and hence, the entropy of the college again increases

(ii) Before the start of any match between the two teams th edisorder is m,inimum as both the teams are on their respective sides but as the game starts players start running and get mixed up in such a situation , the randomness and hence, the entropy increases.

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