Identify the incorrect statements from the following I. $\quad \Delta \mathrm{S}_{\text {system…
Identify the incorrect statements from the following
I. $\quad \Delta \mathrm{S}_{\text {system }}=\left(\Delta \mathrm{S}_{\text {total }}+\Delta \mathrm{S}_{\text {surr. }}\right)$
II. $\mathrm{A}(l) \rightarrow \mathrm{A}(\mathrm{s})$ : for this process entropy change decreases
III. Entropy units are $\mathrm{JK} \mathrm{mol}{ }^{-1}$
I, III only
I, II only
I, II, III
II, III only
Solution
(I) The total entropy change $\left(\Delta \mathrm{S}_{\text {total }}\right)$ for the system and surrounding of a spontaneous process is given by
$\Delta \mathrm{S}_{\text {total }}=\Delta \mathrm{S}_{\text {sys }}+\Delta \mathrm{S}_{\text {surr }}$
(II) $\mathrm{A}(\mathrm{l}) \rightarrow \mathrm{A}(\mathrm{s})$ :
for this process liquid to solid randomness or disorder in the system decreases. So entropy change decreases. entropy will increases in following cases.
(i) $\mathrm{A}(\mathrm{s}) \longrightarrow \mathrm{A}(\mathrm{l})$
(ii) $\mathrm{A}(\mathrm{l}) \longrightarrow \mathrm{A}$ (g)
(iii) $\mathrm{A}(\mathrm{s}) \longrightarrow \mathrm{A}(\mathrm{g})$
(iv) On increasing temperature S will increase
(v) On decreasing pressure, S will increases.
(III) Unit of entropy (S) is $\mathrm{JK}^{-1} \mathrm{~mol}^{-1}$ or $\mathrm{cal} \mathrm{K}^{-1} \mathrm{~mol}$