Question

vapour pressure of benzene and acetone at 298K are 100mm and 300mm of HG respectively calculate the vapour pressure of solution prepared by mixing 20kg of benzene and 42gof acetone at 298K​

Answer 1

Explanation:

It is given that,

PA0=300 mm of Hg

PB0=100mm of Hg

PTotal=100mm of Hg

From Raoults law, we have

 Ptotal=PA+PB

Ptotal=PA0XA+PB0(1−XA)

Ptotal=PA0XA+PB0−PB0XA

Ptotal=(PA0−PB0)XA+PB0

405=(100−300)XA+100

−45=−150XA

 XA=0.3

Therefore,

XB=1−XA

=1−0.3

=0.7

PA=PA0XA

 =100×0.3

 =30mmofHg

PB=PB0×XB

=450×0.7

=315mmofHg

Now in the vapour phase:

Mole fraction of liquid A,

A=(PA+PB)PA=90+31590=0.22

Thus mole fraction of liquid A is 0.22