🌡️ Boiling Point Elevation Calculator
Find how much a solute raises the boiling point: ΔTb = i·Kb·m — or solve for molality, i, or the ebullioscopic constant.
Boiling-point rise ΔTb
0.512 °C
Boiling-point elevation: ΔTb = i·Kb·m. Water Kb = 0.512 °C·kg/mol. i = van’t Hoff factor, m = molality. 🔒 Computed in your browser.
How the boiling point elevation calculator works
Boiling-point elevation is a colligative property: ΔTb = i·Kb·m, where i is the van’t Hoff factor, Kb the ebullioscopic constant (0.512 °C·kg/mol for water), and m the molality. Enter any three and the tool solves for the fourth.
The companion to freezing-point depression. Add ΔTb to the pure solvent’s boiling point (100 °C for water) to get the solution’s boiling point.
Frequently asked questions
What is boiling point elevation?
The rise in a solvent’s boiling point when a solute is dissolved. Like freezing-point depression, it depends on the number of particles: ΔTb = i·Kb·m.
What is Kb for water?
The ebullioscopic constant of water is 0.512 °C·kg/mol. Enter a different Kb for other solvents.
How do I find the new boiling point?
Add ΔTb to the pure solvent’s boiling point. For water that is 100 °C + ΔTb.
What is the van’t Hoff factor here?
The same i as in freezing-point depression — the number of particles per formula unit (NaCl ≈ 2, sugar = 1).
Why is boiling-point elevation smaller than freezing-point depression?
Because Kb (0.512) is smaller than Kf (1.86) for water, the same molality raises the boiling point far less than it lowers the freezing point.