The vapour pressure of two pure liquids A and B, that form an ideal solution are 100 and 900 torr repectively at temperature T. This liquid solution of A and B is composed of 1 mole of A and 1 mole of B. What will be the pressure, when 1 mole of mixture has been vaporized ?

The vapour pressure of two pure liquids A and B, that form an ideal so

1.	The vapour pressure of two pure liquids A and B, that form an ideal solution are 100 and 900 torr repectively at temperature T. This liquid solution of A and B is composed of 1 mole of A and 1 mole of B. What will be the pressure, when 1 mole of mixture has been vaporized ?
Answer» `800` torr `500` torr `300` torr None of these Solution :Let `N_(B)` mole of `B` present in `1` mole of mixture that has been VAPORIZED. Thus `y_(B)=(eta_(B))/(1)` Mole fraction of `B` in the remaining LIQUID phase will be `x_(B)=(1-eta_(B))/(1)` `x_(B)=(P-P_(T)^(@))/(P_(B)^(@)-P_(T)^(@))` ....(1) `[because P=P_(T)^(@)+(P_(B)^(@)-P_(T)^(@))x_(B)]` and `y_(B)=(P_(B))/(P) RARR (P_(B)^(@)x_(B))/(P)` ....(2) After substitution of values of `x_(B)` and `y_(B)` in (1) and (2) we get `1-n_(B)=(P-P_(T)^(@))/(P_(B)-P_(T)^(@))` .....(3) and `n_(B)=((1-n_(B))P_(B)^(@))/(P)` ....(4) or `n_(B)=(P_(B)^(@))/(P+P_(B))` so `1-(P_(B)^(@))/(P+P_(B))=(P-P_(T)^(@))/(P_(B)^(@)P_(T)^(@))` `rArr p=sqrtP_(B)^(@).P_(T)^(@)=sqrt100xx900` `rArr 300` torr