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Solutions

Question
CBSEENCH12005697

Show that the relative lowering of vapour pressure of a solution containing a nonvolatile solute is equal to the mole fraction of the solute in the solution?

Solution

Answer:
Raoult established that the lowering of vapour pressure depends only on the concentration of the solute particles and it is independent of their identity.
establishes a relation between vapour pressure ofthe solution, mole fraction and vapour pressure of the solvent, i.e.

Suppose 1 is solvent 2 is solute
            Psolution = P1 = P01X1

Lowering of vapour pressure
                    = P = P01X1

Lower of vapour pressure
                   = P = P01-P1=  P01(1-X1)

                 P = P01. X2

or             PP10 = X2.