Question

You have a mixture of three liquids A, B and C. There is a large difference in the boiling points of A and rest of the two liquids i.e., B and C. Boiling point of liquids B and C are quite close. Liquid A boils at a higher temperature than B and C and boiling point of B is lower than C. How will you separate the components of the mixture. Draw a diagram showing set up the apparatus for the process.

Answer 1

Since the boiling point of liquid A is much higher than those of liquids B and C whose boiling points are quite close, therefore, separate liquid A by simple distillation using the apparatus shown in Fig. Since the boiling points of liquids B and C are quite close but are much lower than that of liquid A, therefore, mixture of liquids B and C will distill together leaving behind liquid A. On further heating liquid A will distil over.
Now place the mixture of liquids B and C in a flask fitted with a fractionating column as shown in Fig. Since the b.p. of liquid B is lower than that of liquid C, therefore, on fractional distillation, first liquid B will distill over and then liquid C.