Freezing Point Depression Calculator
Use this freezing point depression calculator to estimate how a nonvolatile solute lowers the freezing point of a solvent.
--
Run the calculator.
What This Freezing Point Depression Calculator Helps You Do
This page covers the two most useful freezing-point-depression jobs: predict the new freezing point from solution data, or estimate an unknown molar mass from an experimental freezing-point drop. That keeps the tool useful for both colligative-properties homework and lab interpretation.
The result reports both the depression and the final freezing point so you do not need a second calculation after finding Delta Tf.
How to Calculate Freezing Point Depression Calculator
- Choose the freezing-point workflow: Use molality mode if you know the solution molality, or switch to molar-mass mode if you measured the freezing-point drop experimentally.
- Enter solvent and solute data: The calculator needs the cryoscopic constant and vant Hoff factor, plus either molality or the mass-based solution details.
- Compute Delta Tf: The tool applies the colligative-property equation and reports the temperature drop and the new freezing point.
- Interpret the result: Larger molality or stronger dissociation increases the freezing-point depression.
Freezing Point Depression Calculator Formula
| Variable | Meaning | Unit |
|---|---|---|
| Delta Tf | Freezing point depression | C or K |
| i | vant Hoff factor | dimensionless |
| Kf | Cryoscopic constant of the solvent | C·kg/mol |
| m | Molality | mol/kg |
| Tpure | Freezing point of the pure solvent | C |
Use the worked examples below to check how the formula behaves with real values. If the result looks unexpected, verify the unit assumptions and the meaning of each variable before interpreting the answer.
Worked Examples
- Pure freezing point: 0.0 C
- Kf: 1.86 C·kg/mol
- i: 1
- Molality: 0.50 mol/kg
Result: Delta Tf is 0.93 C and the new freezing point is -0.93 C.
A non-electrolyte causes a moderate freezing-point drop that scales directly with molality.
- Pure freezing point: 0.0 C
- Kf: 1.86 C·kg/mol
- i: 2
- Molality: 0.30 mol/kg
Result: Delta Tf is 1.12 C.
Dissociation increases the number of dissolved particles and therefore the colligative effect.
- Solute mass: 2.50 g
- Solvent mass: 100 g
- Kf: 1.86
- i: 1
- Delta Tf: 0.465 C
Result: Estimated molar mass is about 100 g/mol.
Measured freezing-point depression can be used to infer the solute molar mass if the particle count is known.
- Pure freezing point: 5.5 C
- Kf: 3.90 C·kg/mol
- i: 1
- Molality: 1.20 mol/kg
Result: Delta Tf is 4.68 C and the new freezing point is 0.82 C.
A larger cryoscopic constant and higher molality produce a stronger freezing-point shift.
How to Interpret Your Results
| Range | Meaning | Action |
|---|---|---|
| Small Delta Tf | Low particle concentration or weak dissociation. | Expect only a modest change in freezing point. |
| Moderate Delta Tf | Typical colligative effect for a prepared solution. | Use the result directly for lab or formulation planning. |
| Large Delta Tf | High particle loading or strong dissociation. | Check whether ideal colligative behavior is still a good approximation. |
Frequently Asked Questions
References
Last reviewed: March 2026