Chloroform boils at $\pu{62 ^\circ C}$. For a solution containing $\pu{0.4 g}$ of naphthalene in $\pu{25 g}$ of chloroform, the boiling point is elevated by $\pu{0.45 K}$, to avoid any decomposition during distillation chloroform has to be distilled at $\pu{50 ^\circ C}$, what maximum pressure can be maintained in the flask?

My approach: I found the molality of the solution to be $0.125m$, equating it with the formula $$\Delta T_\mathrm b=K_\mathrm b\cdot m$$ I found $K_\mathrm b$ to be $3.6\ \mathrm{K\ kg/mol}$, I am not able to proceed after this step, please provide an approach to solve the problem from here.

I also tried using the formula $$\Delta K_\mathrm b=\dfrac{R {T_\mathrm b}^2}{1000l_\mathrm v}$$ but finding out the latent heat of vaporisation did not prove to be of any help.

  • $\begingroup$ Apply the Clausius-Clapeyron integral equation, as you know vapour tension at 2 temperatures(on indirectly ). Then you can calculate the tension at the 3rd temperature. $\endgroup$ – Poutnik Aug 15 '20 at 9:44
  • $\begingroup$ Can you provide your approach in detail in the answer, I am not able to apply the Clausius-Clapeyron equeation $\endgroup$ – Shriom707 Aug 15 '20 at 9:45
  • $\begingroup$ I can,but I will not. Try harder. If I consider the time delay of your comment and time to write and post it, you could hardly have a good look at it. Consider also the Raoult law to get the 2nd vapour tension. $\endgroup$ – Poutnik Aug 15 '20 at 9:49
  • $\begingroup$ @Poutnik Is your answer 509.6 torr, I am asking this just to be sure? $\endgroup$ – Shriom707 Aug 15 '20 at 10:36
  • $\begingroup$ Particular answer is of no importance, the principles and procedures are what matters. Otherwise it qualifies well for the closure as a homework-like question. $\endgroup$ – Poutnik Aug 15 '20 at 10:38

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