Question

Enthalpy of vaporization of benzene is $ +35.3kJ $ $ mo{{l}^{-1}} $ at its boiling point, $ 80{}^\circ C $ . The entropy change in the transition of the vapour to liquid at its boiling point [in $ J{{K}^{-1}}mo{{l}^{-1}} $ ]is

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

Answer 1

Answer: (B)

Entropy change in the transition of the vapour to liquid, $ {{\Delta }_{cond}}S=\frac{\Delta {{H}_{cond}}}{{{T}_{b}}}=\frac{-35.5\times {{10}^{3}}J\,mo{{l}^{-1}}}{(80+273)K} $ $ =-100J{{K}^{-1}}mo{{l}^{-1}} $