Boiling Point Elevation Calculator
Boiling point elevation calculator: how much a solute raises the boiling point, or the molality needed.
ΔTb = i · Kb · b
How to use this calculator
- Choose the quantity you want under “Solve for”.
- Type the known values and pick their units: any combination works.
- The result updates as you type. Open “Show the steps” to see the substitution.
ΔT_b = i·K_b·b, where b is the molality (mol of solute per kg of solvent). For water K_b = 0.512 K·kg/mol.
Formula
ΔTb = i · Kb · b
| Symbol | Quantity | Units |
|---|---|---|
| i | van 't Hoff factor | — |
| Kb | Ebullioscopic constant (water 0.512) | K·kg/mol |
| b | Molality | mol/kg, mmol/kg |
| ΔTb | Boiling point rise | K, °C, °F |
Worked example
Given: i = 2 · Kb = 0.512 K·kg/mol · b = 1 mol/kg
ΔT = i Kb b
Result: ΔTb = 1.024 °C
Frequently asked questions
1 mol/kg of NaCl (i = 2) in water?
The boiling point rises 1.02 °C, to about 101.0 °C.