Important Relations Concerning Elevation In Boiling Point

(1) The elevation of boiling point is directly proportional to the lowering of vapour pressure, i.e., 

(2)  where  molal elevation constant or ebullioscopic constant of the solvent;   Molality of the solution, i.e., number of moles of solute per  of the solvent;   Elevation in boiling point

(3)  or 

where,  is molal elevation constant and defined as the elevation in b.pt. produced when 1 mole of the solute is dissolved in 1 kg of the solvent.

 and  are the weights of solute and solvent and  is the molecular weight of the solute.

(4)  

where  Normal boiling point of the pure solvent; Latent heat of evaporation in  of pure solvent;  for water is .