Two liquids A and B are miscible over the whole range of composition and may be treated as ideal (obeying Raoult's law.) At 350K the vapour pressure of pure A is 24.0kPa and of pure B is 12.0 kPa. A mixture of 60% A and 40% B is distilled at this temperature, what is the pressure in a closed distillation apparatus from which air is exclued ? A small amount of the distillate is collected and and redistilled at 350K What is the composition

Two liquids A and B are miscible over the whole range of composition a

1.	Two liquids A and B are miscible over the whole range of composition and may be treated as ideal (obeying Raoult's law.) At 350K the vapour pressure of pure A is 24.0kPa and of pure B is 12.0 kPa. A mixture of 60% A and 40% B is distilled at this temperature, what is the pressure in a closed distillation apparatus from which air is exclued ? A small amount of the distillate is collected and and redistilled at 350K What is the composition
Answer» Solution :`P_(T)=(6)/(10)xx24+(0.4)/(10)xx12(16xx12)/(10)=(192)/(10)=19.2kPa` `P_(A)'=X_(A)P_(A)=(6)/(10)xx24(144)/(10)=14.4=X_(A)'xx19.2` so `X_(A)'=(144)192)=75% X_(A)'=25%` so `P_(T)=(3)/(4)xx24+(1)/(4)xx12=18+3=21kPa` `& P_(A)=(3)/(4)xx24=18=X_(A)'(21)` so `X_(A)'=(18)/(21)=(6)/(7)=85.7%` of` A`