Question

The vapour pressure of a dilute aqueous solution of glucose is $750mm$ of $Hg$ at $373K$. The mole fraction of solute is.

• A. $\frac{1}{76}$
• B. $\frac{1}{7.6}$
• C. $\frac{1}{35}$
• D. $\frac{1}{10}$

Answer 1

The correct option is A $\frac{1}{76}$

$\Rightarrow$ Temperature $373K,p^o=760mm$ and $p^s=750mm$

So, from the Rault law,

$\Rightarrow$ Mole fraction $=\frac{p^o-p^s}{p^o}$

$\Rightarrow$ Mole fraction $=\frac{760-750}{760}$

$\therefore$ Mole fraction $=\frac{10}{760}=\frac{1}{76}$