Two liquids A and B have vapour pressures in the ratio PÅ :P = 2:3 at a certain temperatu
allo PA : PB = 2:3 at a certain temperature. Assuming that
A and B form an ideal solution and ratio of mole fractions of A to B in the vapour phase is
B in the vapour phase is 1:3, then the
mole fraction of A in the solution at the same temperature is
Answers
Answer:
The mole fraction of A in the solution at the same temperature is 1/3.
Explanation:
Given data:
Two liquids A and B have vapour pressures in the ratio PA :P = 2:3 at a certain temperature.
PA : PB = 2:3
P° = 2+3 = 5
A and B form an ideal solution.
ratio of mole fractions of A to B in the vapour phase is B in the vapour phase =
1:3
To find,
mole fraction of A in the solution at the same temperature =?
Solution
Mole fraction of A = 1/4
Mole fraction of B = 3/4
We know that the formula for Partial pressure is given by
PA = XA*P°
PA = (1/4) *5
= 1.25
Where XA is the mole fraction
P° = vapour pressure of pure solvent
PA=new vapour pressure.
Also similarly for PB
PB = XB*P°
PB =( 3/4) * 5
= 3.75
Where XB is the mole fraction
P° = vapour pressure of pure solvent
PB=new vapour pressure.
So now
Taking the ratip of PA/PB
PA/PB = XA*P°/XB*P°
As we have to calculate the mole fraction,
PA/PB = 1.25/3.75
= 1/3 = XA
Hence,
The mole fraction of A in the solution at the same temperature is 1/3.