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Freezing Point Depression Calculator.

Calculate freezing-point depression with the van't Hoff factor, cryoscopic constant, and molality.

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Freezing-point depression: 3.72 K

Freezing-point depression

3.720000K

Educational chemistry arithmetic only. Keep units consistent and verify assumptions against your laboratory or course specification.

Use Cases

Chemistry Lab Calculations

Determine the freezing point depression of a solution for experiments or to verify colligative properties. Useful for students and researchers.

Example: Calculate ΔTf for 0.5 mol/kg NaCl (i=2) in water (Kf=1.86 K·kg/mol).

Antifreeze and De-icing Solutions

Estimate how much a solute lowers the freezing point of a liquid, which is important for formulating antifreeze or road de-icers.

Example: Find the freezing point depression for a 1.0 mol/kg ethylene glycol solution (i=1).

Frequently Asked Questions

What is freezing-point depression?
Freezing-point depression is the lowering of a solvent's freezing point when a solute is added. It depends on the number of solute particles in solution, not their identity. This calculator uses the van't Hoff factor, cryoscopic constant, and molality to compute the temperature change.
How do I use the van't Hoff factor?
The van't Hoff factor (i) accounts for the number of particles a solute dissociates into. For non-electrolytes, i=1. For strong electrolytes like NaCl, i≈2. Enter the appropriate value for your solute to get an accurate freezing-point depression.
What units are used in this calculator?
The cryoscopic constant is in K·kg/mol, and molality is in mol/kg. The van't Hoff factor is dimensionless. The result is the freezing-point depression in Kelvin (K), which is numerically equal to °C change.

Tips & Common Mistakes

Tips

  • Ensure the van't Hoff factor matches your solute: 1 for non-electrolytes, 2 for NaCl, 3 for CaCl2, etc.
  • Use molality (mol/kg) not molarity (mol/L) for accurate colligative property calculations.
  • Check the cryoscopic constant for your specific solvent (e.g., water: 1.86 K·kg/mol).
  • Remember that the result is the depression (ΔTf), not the actual freezing point. Subtract from the pure solvent's freezing point if needed.

Common Mistakes to Avoid

  • Using molarity instead of molality – molality is moles of solute per kilogram of solvent.
  • Forgetting to include the van't Hoff factor for ionic compounds, leading to underestimated depression.
  • Using the wrong cryoscopic constant for the solvent – each solvent has its own value.

Last updated: August 13, 2026