Intext Question

Intext Question . The vapour pressure of pure liquids A and B are and mm Hg respectively, at K . Find out the composition of the liquid mixture if total vapour pressure is mm Hg. Also find the composition of the vapour phase. . . Relative Lowering of Vapour Pressure The expression on the left hand side of the equation as mentioned earlier is called relative lowering of vapour pressure and is equal to the mole fraction of the solute . The above equation can be written as: p – p since       ( . ) Here n and n are the number of moles of solvent and solute respectively present in the solution. For dilute solutions n < < n , hence neglecting n in the denominator we have ( . ) or - w × × w M M ( . ) Here w and w are the masses and M and M are the molar masses of the solvent and solute respectively. From this equation ( . ), knowing all other quantities, the molar mass of solute ( M ) can be calculated.