About this tool
The Colligative Properties Calculator is a free, in-browser chemistry tool for the four colligative effects that depend on the amount of dissolved particles rather than their identity. Pick a solvent to load its cryoscopic constant Kf and ebullioscopic constant Kb, enter the molality of the solution and the van't Hoff factor i, and it returns the freezing-point depression, boiling-point elevation, the shifted freezing and boiling points, and the osmotic pressure.
Freezing-point depression is ΔTf = i · Kf · b and boiling-point elevation is ΔTb = i · Kb · b, where b is molality in mol/kg; the new points are (normal freezing point − ΔTf) and (normal boiling point + ΔTb). Osmotic pressure uses π = i · M · R · T with molarity M in mol/L, absolute temperature T in kelvin, and the gas constant R = 0.08206 L·atm/mol·K, giving π in atmospheres.
All calculations run locally in your browser, so nothing you enter is uploaded. The van't Hoff factor i is 1 for a non-electrolyte (like sugar), about 2 for NaCl and 3 for CaCl₂, accounting for the particles a solute releases. Choosing Custom lets you type your own Kf and Kb; the shifted freezing/boiling points then reference 0 °C and 100 °C.