State and explain :
Raoult's law for volatile solute.

Explanation

Raoult.s law for volatile solute . In a solution the vapour pressure of component at a given temperature is directly proportional to its mole fraction. For example, if we have two miscible liquids A and B then
`p_(A) prop x_(A) or p_(A) = p_(A)^(@) xx x_(A)`
`p_(B) prop x_(B) or P_(B) = p_(B)^(@) xx x_(B)`
where `x_(A) and x_(B)` are mole fraction of A and B respectively . `p_(A)^(@) and p_(B)^(@)` are vapour pressure of A and B respectively in pure state
Is `p_(s)` is total vapour pressure of the solution at same temperature then according to Dalton.s law of partial pressures
`p_(s) = p_(A) + p_(B)`
`p_(s) = p_(A)^(@) + p_(B)^(@) x_(B)`