Question

Given at 350 K $p_A^o$ = 300 torr and $p_B^o$ = 800 torr, the composition of the mixture having a normal boiling point of 350 K is:

• A. $X_A=0.08$
• B. $X_A=0.06$
• C. $X_A=0.04$
• D. $X_A=0.02$

Answer 1

Answer: (A)

$X_A=0.08$

$\begin{array}{cc}\text{As}{P}_t& =X_A{P}_A^0+X_B{P}_B^{\circ }\\ & \text{as}{X}_B=1-X_A\end{array}$

$\begin{array}{c}\text{as its given that solution boils at}\\ \text{normal boiling point i.e.}760\text{tor}\end{array}$

$\begin{array}{cc}\text{So,}760& =X_A\left(300\right)+(1-X_A)800\\ \Rightarrow & \text{solving it we get}{X}_A=0.08\end{array}$