Question

Benzene and naphthalene form an ideal solution at room temperature. For this process, the true statement(s) is (are)

• A. $\Delta G$ is positive
• B. $\Delta S_{system}$ is positive
• C. $\Delta S_{surroundings} = 0$
• D. $\Delta H = 0$

Answer 1

Answer: (B), (C), (D)

PLAN When an ideal solution is formed process is spontaneous thus
According to Raoult's law, for an ideal solution
$\, \, \, \, \, \, \, \, \, \, \, \, \Delta H = 0, \Delta V_{mm} = 0$
From the relation
$ \, \, \, \, \, \, \, \, \, \, \, \, \, \, \Delta G = \Delta H - T \Delta S$
Since, $\, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \, \Delta H = 0$
$\therefore \, \, \, \, \, \, \, \, \, \, \Delta G = - ve$
i.e. less than zero, and $\Delta S_{sys} = + ve$
i.e. more than zero.