Question

Enthalpy of vapourization of benzene is $+35.3 \, kJ \, mol^{-1}$ at its boiling point of $80^{\circ} C$.
The entropy change in the transition of the vapour to liquid at its boiling point [in $JK^{-1} \, mol ^{-1}$ ] is ________

• A. $-100$
• B. $-441$
• C. $+100$
• D. $+441$

Answer 1

Answer: (C)

Entropy change in the transition of the vapour to liquid,

$\Delta_{\text {cond }} S =\frac{\Delta H_{\text {cond }}}{T_{b}}$

$=\frac{35.3 \times 10^{3} J mol ^{-1}}{(80+273) K }$

$=100\, JK ^{-1} mol ^{-1}$