How this calculator works
Dissolved nonvolatile particles lower solvent vapour pressure, so a higher temperature is required to boil. Multiply the solvent ebullioscopic constant by solute molality and the effective particle factor, then add the change to the pure-solvent boiling point. Molality means moles per kilogram of solvent, not per litre of solution. Presets are rounded reference values near one atmosphere. Custom data lets you use a protocol-specific constant. These dilute-solution equations do not describe concentrated mixtures or eutectics.
Formula
DeltaTb = i Kb m; Tsolution = Tpure + DeltaTb. m is mol/kg solvent; K is K kg/mol. A temperature difference of 1 K equals 1 Celsius degree.
Worked example
With water Kb = 0.512 K kg/mol, 1 mol/kg nonelectrolyte raises the boiling point by 0.512 K, to 100.512 C. A 0.5 mol/kg solute with i = 2 gives the same change.
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Frequently asked questions
Is molality the same as molarity?
No. Molality uses kilograms of solvent; molarity uses litres of final solution.
How should I choose the van't Hoff factor?
Use an experimentally appropriate value; ideal complete dissociation is only an approximation.
Can I solve a solvent constant?
Yes. Select solvent constant and provide a measured temperature-change magnitude, molality and particle factor.