Boiling point elevation refers to the increase in the boiling point of a solvent upon the addition of a solute. When a non-volatile solute is added to a solvent, the resulting solution has a higher boiling point than that of the pure solvent.
Boiling Point Elevation Formula
The boiling point of a solution containing a non-volatile solute can be expressed as follows:
Boiling point of solution = boiling point of pure solvent + boiling point elevation (ΔTb)
The elevation in boiling point (ΔTb) is proportional to the concentration of the solute in the solution. It can be calculated via the following equation.
ΔTb = i*Kb*m
- i is the Van’t Hoff factor
- Kb is the ebullioscopic constant
- m is the molality of the solute
The ebullioscopic constant (Kb) is often expressed in terms of oC/molal or oC.kg.mol-1.