Chemical Thermodynamics — Chemistry STD 12 Science — Question
Maharashtra BoardEnglish MediumSTD 12 ScienceChemistryChemical Thermodynamics3 Marks
Question
What is entropy? Give its units.
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Answer
(i) Entropy : Being a state function and thermodynamic function it is defined as entropy change $(\Delta S)$ of a system in a process which is equal to the amount of heat transferred in a reversible manner ( $Q_{\text {rev }}$ ) divided by the absolute temperature $(T),$ at which the heat is absorbed. Thus,
$ \text { Entropy change }=\frac{\text { Heat transferred reversibly }}{\text { Absolute temperature of heat transfer }}$
$\therefore \Delta S=\frac{Q_{\text {rev }}}{ T } \quad \text { } $
(ii) Units of entropy are $JK ^{-1}$ in $SI$ unit and cal $K ^{-1}$ in c.g.s. units. It is also expressed in terms of entropy unit (e.u.). Hence 1 e.u. $=1 JK ^{-1}$.
(iii) Entropy is a measure of disorder in the system. Higher the disorder, more is entropy of the system.
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