Question

Consider a binary mixture of volatile liquids. If at $X_{A} = 0.4$ the vapour pressure of solution is 580 torr then the mixture could be $(p_{A}^{\circ}=300$ torr, $p_{B}^{\circ}=800$ torr) :

• A. $CHCl_{3} - CH_{3}COCH_{3}$
• B. $C_{6} H_{5} Cl - C_{6} H_{4}Br$
• C. $C_{6}H_{6}-C_{6}H_{5}CH_{3}$
• D. $nC_{6} H_{14}-n\,C_{7} H_{16}$

Answer 1

Answer: (A)

It shows negative deviation from Raoult’s law
$p_{s}$ (actual) = 580 torr
$p_{s}$ (Raoult) $ = 0.4 \times 300+0.6\times 800 = 600$ torr