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Colligative Properties Calculator

Work out colligative properties instantly with clear inputs, formula shown and shareable results.

About Colligative Properties Calculator

Colligative properties depend on how many dissolved particles there are, not what they are. Freezing point falls by i.Kf.m and boiling point rises by i.Kb.m, where i counts the particles each formula unit releases. One molal sodium chloride (i = 2) in water depresses freezing by 3.72 K and raises boiling by about 1.02 K.

Formulas

Freezing point depression

dTf = i x Kf x molality

Boiling point elevation

dTb = i x Kb x molality

Worked example

With the default values below, Colligative Properties Calculator returns Freezing Point Depression of 3.720. Change any input above and every figure here is recalculated in your browser.

Inputs used

Solute molalityminimum 0 mol/kg
1 mol/kg
van't Hoff factor iminimum 0.1
2
Freezing point depression constant Kfminimum 0 K kg/mol
1.86 K kg/mol
Boiling point elevation constant Kbminimum 0 K kg/mol
0.512 K kg/mol

Results

Freezing Point Depression
3.720 K
Boiling Point Elevation
1.024 K
Solution Freezing Point
-3.720 C
Solution Boiling Point
101.024 C

Step by step

  1. 1Values used
  2. 2Freezing point depression
  3. 3Boiling point elevation
  4. 4Freezing Point Depression= 3.720 K
  5. 5Boiling Point Elevation= 1.024 K
  6. 6Solution Freezing Point= -3.720 C
  7. 7Solution Boiling Point= 101.024 C

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What is the van't Hoff factor?

The number of particles a formula unit produces in solution: 1 for sugar, 2 for NaCl, 3 for CaCl2. Real values fall slightly short because of ion pairing.

Why molality rather than molarity?

Because molality uses solvent mass, which does not change with temperature. Molarity would drift as the solution expanded or contracted.

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