QJEEAdv08Ch0c19: JEE Advanced 2008 Chemistry - Class 12 JEEAdv08Ch0c19 Solution: Water is added to the solution M such that the fraction of…

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Water is added to the solution M such that the fraction of water in the solution becomes 0.9 mole. The boiling point of this solution is:

Accepted Answer

$\begin{matrix} \underset{(Solute \equiv B)}{x_{e t h a n o l} = 0.1} & : & \underset{(Solvent \equiv A)}{x_{w a t e r} = 0.9} \end{matrix}$

$\Delta {T_b} = {K_b}\,.\,m = {K_b}\,.\,{{{x_B}} \over {1 - {x_B}}} \times {{1000} \over {{M_{{w_A}}}}}$

$= 0.52 \times {{0.1} \over {0.9}} \times {{1000} \over {18}} = 3.2\,K$

${T_b} = T_b^0 + \Delta {T_b} = 373 + 3.2 = 376.2\,K$

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