Class 12th "Solutions"
1. Vapour P ressure Lowering : when we adding a vapourised solute in the normal solvent there after changed in vapour pressure is called lowering of vapour pressure. If any of pure solvent vapour pressure is p° and vapour pressure of solution is p, Than, lowering of vapour pressure = p°-p And relative lowering of vapour pressure = p°-p/p° [A] Measurement of Relative Lowering of Vapour Pressure : for the measurement the Ostward and Walker's dynamic method is most important method to measurement. [B] Determination of molecular mass of a solute from Relative Lowering of Vapour Pressure : The formula of the calculating the molecular mass of solute as Where, M' = molecular weight of solute. w = molar mass of solute. W = molar mass of solvent. M = molecular weight of solvent. • Elevation of ...