State Raoult's law for a solution containing volatile liquids. Explain with suitable example the concept of maximum boiling azeotropes.

Explanation

Raoult.s law : For a solution of volatile liquids, the partial vapour pressure of each component in the solution is directly proportional to its mole fraction. Let us say that there are two components 1 and 2 in a solution.
For component 1,
`p_1 prop x_1` ,
where `p_1` and `x_1` are partial pressure and mole fraction of component 1. and
`p_1 p_1^0 x_1`
where `p_1^0` is the vapour pressure of pure component 1 at the same temperature. Similarly for component 2,
`p_2 = p_1^0x_2`
Maximum boiling azeotropes : Solutions that show large negative deviations from Raoult.s law form maximum boiling azeotropes at a specific composition. Nitric acid and water is an example of this type of azeotropes. This azeotrope has the approximate composition, 68% nitric acid and 32% water by mass, with a boiling point of 393.5 K.