Which of the following statements about the composition of the vapour over an ideal 1: 1 molar mixture of benzene and toluene is correct? Assume that the temperature is constant at 25°C. (Given, Vapour Pressure Data at 25°C, benzene = 12.8 kPa, toluene = 3.85 kPa)
The vapour will contain a higher percentage of benzene.
The vapour will contain a higher percentage of toluene.
The vapour will contain equal amounts of benzene and toluene.
Not enough information is given to make a prediction.
As we learned in concept
Nature of liquid and vapour pressure -
Liquids which are more volatile exerts more vapour pressure.
- wherein
More volatile liquids are those when intermolecular forces are weak.
When we look at vapour pressure data of lengene (12-8 kPa) and toluene (3.85 kPa) we find that lengene is more volatile than toluene and hence will exert grater pressure and will have higher percentage in vapour phase
Option 1)
The vapour will contain a higher percentage of benzene.
Option is correct
Option 2)
The vapour will contain a higher percentage of toluene.
Option is incorrect
Option 3)
The vapour will contain equal amounts of benzene and toluene.
Option is incorrect
Option 4)
Not enough information is given to make a prediction.
Option is incorrect