Question

A mixture of two immiscible liquids $A$ and $B$, having vapour pressure in pure state obeys the following relationship if $\chi_{ A }$ and $\chi_{ B }$ are mole fractions of $A$ and $B$ in vapour phase over the solution

• A. $P _{ A }^{\prime}= P _{ M } \chi_{ A }^{\prime}$
• B. $\frac{P_{ A }^{\prime}}{P_{ B }^{\prime}}=\frac{W_{ A } \times M w_{ B }}{M w_A \times W_{ B }}$
• C. If $P_{ A }^{\prime}>P_{ B }^{\prime}$ then $\chi_{ A }^{\prime}<\chi_{ B }^{\prime}$
• D. If $P_{ A }^{\prime}>P_{ B }^{\prime}$ then $n_{ A }>n_{ B }$

Answer 1

Answer: (A), (B), (D)

For immiscible liquids
$P_{ A }^{\prime}=P_{ M } \cdot \chi_{ A }^{\prime} ; P_{ B }^{\prime}=P_{ M } \cdot \chi_{ B }{ }^{\prime}$
$\therefore \frac{P_{ A }^{\prime}}{P_{ B }^{\prime}}=\frac{\chi_{ A }^{\prime}}{\chi_{ B }^{\prime}}=\frac{n_{ A }}{n_{ B }}=\frac{W_{ A } \times M w_{ B }}{M w_{ A } \times W_{ B }}$
If $P_A^{\prime}> P _{ B }{ }^{\prime}$, then $n_{ A }>n_{ B }$