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Chemistry

Boiling and Freezing Point Calculator

Estimate boiling-point elevation and freezing-point depression from molality and solvent constants.

Explicit units and model assumptionsLocal calculations with worked examples
Chemistry workspace
Chemistry workspace

Check the units, concentration basis and assumptions before interpreting the result.

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Your chemistry result

Your result

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Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter solution molality, van’t hoff factor, boiling-point elevation constant kb, freezing-point depression constant kf, pure solvent boiling point, pure solvent freezing point.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

ΔTb = i·Kb·m and ΔTf = i·Kf·m. Add ΔTb to the pure boiling point and subtract ΔTf from the pure freezing point.

A WORKED EXAMPLE

Using solution molality = 1 mol/kg, van’t hoff factor = 1, boiling-point elevation constant kb = 0.512 K·kg/mol, freezing-point depression constant kf = 1.86 K·kg/mol, pure solvent boiling point = 100 °C, pure solvent freezing point = 0 °C, the result is 100.512 °C boiling point. Change these example inputs to match your task; use the method above to check each step.

Understanding your result

No. Ideal dissociation suggests a factor, but association and ion interactions may reduce the observed particle effect. Use an experimentally appropriate value.

What to keep in mind

Dilute ideal solution with a nonvolatile solute. Use empirical van’t Hoff factors when ion interactions matter. Pure-solvent boiling point depends on pressure. Educational calculation only; use validated procedures for laboratory work.

Reference: OpenStax Chemistry 2e — chemical quantities and models

Common questions

Is the factor always the number of ions in the formula?

No. Ideal dissociation suggests a factor, but association and ion interactions may reduce the observed particle effect. Use an experimentally appropriate value.

Are my inputs uploaded?

No. This calculation runs in your browser without an account or an external API.

Methodology maintained by ClarityKit. How these tools are built and checked.