Organic Chemistry

1. State true or false a) Raoult’s law states that the partial vapor pressure of component A in solution (PA)

equals the vapor pressure of pure A (POA) times its mole fraction (NA), i.e., PA = POA X NA

b) During distillation, one should continue heating until the distilling flask runs dry to ensure good yield

c) Fractional distillation is generally used to achieve separation of two liquids with similar boiling points

2. The boiling point of toluene at 1 atm is 110 oC. What is its vapor pressure at this temperature?

3. Under what conditions can a good separation be achieved by simple distillation?

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4. Why must each component being analyzed by GC have a specific correction factor to convert the peak areas on the GC chromatogram to relative masses?

5. Calculate the vapor pressure of an equimolar mixture of cyclohexane and toluene at 50 oC. Assume that this is an ideal mixture. Given: Vapor pressure of cyclohexane at 50 oC is 272 mmHg

Vapor pressure of toluene at 50 oC is 92 mmHg

6. Draw a plot of temperature v/s volume for a) Simple distillation b) Fractional distillation

7. Given below is a phase diagram showing the relationship between the composition of the liquid phase and the gas phase of a solution of A and B

Volume 

Te m

pe ra

tu re



Volume 

Te m

pe ra

tu re



Te m

pe ra

tu re

( o C

) 

Te m

pe ra

tu re

( o C

) 

% Composition 

a) What is the molar composition of the vapor in equilibrium with a boiling liquid that has the composition of 70% A and 30% B?

b) A sample of vapor has the composition 50% A and 50% B. What is the composition of the liquid that produced the vapor?

c) What is the boiling point of a liquid that has the molar composition of 30% A and 70% B?

8. Label the proper places for water in and out on the condenser below: