Answer to Question #153322 in Physical Chemistry for Fletcher Madden

Question

A mixtureof ethanol (bp 78.50C) and water(bp 1000c) shows a positive deviation from Raoult´s law and forms an ayotropic mixture of boiling point 78.20C at a composition of 96% ethanol.

i)What is an azotropic mixture.

ii)Draw a well labeled diagram of the boiling point against composition of water-ethanol mixture.

Answer 1

azeotropic mixture, constant boiling mixture. Azeotrope, in chemistry, a mixture of liquids that has a constant boiling point because the vapour has the same composition as the liquid mixture. The boiling point of an azeotropic mixture may be higher or lower than that of any of its components.

Types of Azeotropes

• Positive azeotrope or minimum boiling azeotrope.
• Negative azeotrope or maximum boiling azeotrope.
• Heterogeneous azeotrope.
• Homogeneous azeotrope.
• Binary azeotrope.
• Ternary azeotrope.

Azeotropic distillation is the use of a third component to separate two close-boiling components. This is done by means of the formation of an azeotropic mixture between one of the original components and the third to increase the difference in the boiling points and facilitate separation by distillation.