Boiling Point Elevation Calculator

C
C kg/mol
For water: 0.512 C kg/mol
mol/kg
1 for non-ionic compounds, ~2 for salts, ~3 for trisalts
Chemistry

Calculate boiling point elevation — how much a dissolved solute raises a solvent's boiling point. Enter the solvent's boiling point, the ebullioscopic constant, molality, and van't Hoff factor to get the elevation and the new boiling point.

Formula

ΔTb = i × Kb × m, where ΔTb = boiling point elevation, i = van't Hoff factor, Kb = ebullioscopic constant, m = molality
  • Boiling Point Elevation Calculator gives you a fast estimate using your inputs and updates instantly when you change any value.
  • Formula: ΔTb = i × Kb × m, where ΔTb = boiling point elevation, i = van't Hoff factor, Kb = ebullioscopic constant, m = molality
  • Input definitions: • Pure solvent boiling point: the numeric pure solvent boiling point used in the calculation • Boiling point elevation constant (Kb): the numeric boiling point elevation constant (kb) used in the calculation • Molality (m): the numeric molality (m) used in the calculation • van't Hoff factor (i): the numeric van't hoff factor (i) used in the calculation
  • Manual method: write down each input, apply the formula step by step, then compare your manual result with the calculator output.
  • Uses standard SI and chemistry units (mol, L, g/mol, M, Pa, K) unless otherwise stated.
  • Based on standard stoichiometric and thermodynamic equations. Results may vary with temperature, pressure, and substance purity.
  • Cross-check results against known standards or reference tables to confirm they are physically reasonable.
  • Practical tip: test a low, medium, and high scenario to understand sensitivity before making decisions.

Example Calculation

Inputs
  • Pure solvent boiling point: 100 C
  • Boiling point elevation constant (Kb): 0.512 C kg/mol
  • Molality (m): 1 mol/kg
  • van't Hoff factor (i): 1

Suppose you enter: Pure solvent boiling point = 100, Boiling point elevation constant (Kb) = 0.512, Molality (m) = 1, van't Hoff factor (i) = 1. The calculator applies the formula (ΔTb = i × Kb × m, where ΔTb = boiling point elevation, i = van't Hoff factor, Kb = ebullioscopic constant, m = molality) and shows all output values below. Change any input field to immediately see how the result changes.

Frequently asked questions

What is boiling point elevation?
It is the increase in a liquid's boiling point when a non-volatile solute is dissolved in it — a colligative property that depends on the amount of solute, not its identity.
What is the van't Hoff factor?
It is the number of particles a solute breaks into in solution: 1 for sugar, about 2 for NaCl, and about 3 for CaCl₂.
What is the ebullioscopic constant (Kb)?
It is a solvent-specific constant relating molality to boiling point rise. For water it is 0.512 °C·kg/mol.
What is molality?
Molality is moles of solute per kilogram of solvent. It is used here instead of molarity because it does not change with temperature.
Why do salts raise boiling point more than sugar?
Salts dissociate into multiple ions, so they add more dissolved particles per mole, increasing the elevation through the van't Hoff factor.