What Is a Boiling Point Elevation Calculator?
Boiling point elevation is a colligative property: dissolving any solute in a solvent raises the solvent's boiling point, and the size of the increase depends only on the number of dissolved particles, not their chemical identity. This calculator computes molality from solute mass, molar mass and solvent mass, then applies ΔTb = i·Kb·m to find the new boiling point.
It's the same principle behind why adding solutes to a liquid — from salt in cooking water to antifreeze in an engine's coolant — nudges its boiling point higher.
How to Read Your Results
New Boiling Point
The temperature at which the solution will begin to boil, after accounting for the dissolved solute.
Molality
Moles of solute per kilogram of solvent, the concentration unit used for colligative properties because it's independent of temperature and pressure.
Boiling Point Elevation (ΔTb)
How many degrees the boiling point rises above the pure solvent's boiling point.
Moles of Solute
The total moles of solute dissolved, calculated as solute mass ÷ solute molar mass.
Real-World Example
Dissolving 10 g of table salt (NaCl, molar mass 58.44 g/mol, i = 2) in 1 kg of water (Kb = 0.512 °C·kg/mol, pure boiling point 100 °C):
| Quantity | Value |
|---|---|
| Moles of NaCl | 10 ÷ 58.44 ≈ 0.1711 mol |
| Molality | 0.1711 mol/kg |
| ΔTb | 2 × 0.512 × 0.1711 ≈ 0.18 °C |
| New boiling point | 100 + 0.18 ≈ 100.18 °C |
The salted water needs to reach about 100.18 °C before it boils — a small but measurable rise above pure water's 100 °C boiling point.
Tips for Accurate Results
- Use the correct van't Hoff factor for ionic compounds — dissociation multiplies the effect on both freezing and boiling points.
- Common Kb values: water 0.512, benzene 2.53, chloroform 3.63 °C·kg/mol.
- This is an ideal-solution approximation — very concentrated solutions can deviate from ideal, linear behavior.
- Boiling point elevation and freezing point depression are governed by the same molality, just with different solvent-specific constants and opposite directions.
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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team