Define ebullioscopic constant?

The ebullioscopic constant is a solvent’s fixed value that tells how much its boiling point rises when one mole of solute is dissolved per kilogram of that solvent. 

It is the proportionality constant K_b in the boiling point elevation formula. The ebullioscopic constant, written as K_b, measures the sensitivity of a pure solvent’s boiling point to the presence of a non-volatile solute. If you add a solute, the boiling point goes up. The rise in temperature is directly proportional to the molality of the solution.

Key formula: ΔT_b = K_b × m × i, where:

• ΔT_b = elevation in boiling point.
• K_b = ebullioscopic constant of the solvent.
• m = molality of the solute (moles per kg of solvent).
• i = van ’t Hoff factor (accounts for ionization or association).