. Define molal elevation constant or ebullioscopic constant

Best Answer


When a non volatile solute is added to a solvent then its vapor pressure decrease. Also Boiling point  is the temperature at which vapor pressure of liquid becomes equal to Vapour pressure of surrounding. 

Now as vapor pressure decreases we need to provide more energy to the system and hence the boiling point of the solvent increases. 

This increase in boiling point is directly related to molality “m” as

molal elevation

To remove propotanility

molal elevation

This Constant is called  elevation constant or ebullioscopic constant.

When molality =1 then molal elevation


Final answer:- 

When 1 mole of solute is dissolved in a hundred gram of solvent then the elevation in boiling point becomes equal to molal elevation constant. 

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