Question

Post Lab Questions Fermentation:

1. What physical property enables one to use distillation for the separation of ethyl alcohol enriched from the water mixture?

2 What is an Azeotrope? Explain how can azeotropes be used to purify mixtures?

3. Azeotropes are also defined as liquid mixtures having a vapor pressure at constant temperature, as a function of composition. Explain with your own words why vapor pressure depends on the composition of the mixture.

4 If the distillation temperature is different from the theoretical distillation temperature, why do you think this is so?

Answer 1

1) The physical property called condensation in which the alcohol is condensed helps in separating ethyl alcohol enriched from the water mixture.

2) Azeotrope is a mixture of liquids which have constant boiling point. As azeotropes have high boiling point so materials are added to form azeotropes mixture with the substance to be purified as they boils at different temperature so separation from substance distilling in same range as pure material.

3) The total vapor pressure of this solution varies with the mole fraction composition of the mixture.vapor pressure of a liquid increases nearly exponentially as a function of temperature.At different fixed temperature the total vapor pressure at the azeotropic composition will change.

4) Beacuse azeotropes have constant boiling mixture and are minimum boiling azeotrope and maximum boiling azeotrope.