Boiling Point Elevation Calculator
Calculate how much a dissolved solute raises the boiling point of a solvent.
About Boiling Point Elevation Calculator
Boiling point elevation is a colligative property, depending only on particle count rather than identity. Electrolytes dissociate, so the van’t Hoff factor multiplies the effect. The effect is small: even 1 molal salt raises water’s boiling point by only about one degree, which is why salting pasta water is about flavour rather than cooking speed.
Formula
Boiling Point Elevation
ΔT_b = i K_b b, with i the van’t Hoff factor
- K_b
- Ebullioscopic constant, 0.512 K·kg/mol for water
- i
- Particles released per formula unit — 2 for NaCl, 1 for sugar
Worked example
With the default values below, Boiling Point Elevation Calculator returns Boiling Point Elevation of 1.0240. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Molality of the solutionminimum 0 mol/kg
- 1 mol/kg
- Ebullioscopic constantminimum 0 K kg/mol
- 0.512 K kg/mol
- Van’t Hoff factoraccepts 1–10
- 2
- Normal boiling pointaccepts -100–500 C
- 100 C
Results
- Boiling Point Elevation
- 1.0240 K
- New Boiling Point
- 101.024 C
- Effective Particle Molality
- 2.0000 mol/kg
- Molality Needed for a One-Degree Rise
- 0.9766 mol/kg
- Interpretation
- Electrolyte — dissociation multiplies the effect
Step by step
- 1Values used
- 2Boiling Point Elevation
- 3Boiling Point Elevation= 1.0240 K
- 4New Boiling Point= 101.024 C
- 5Effective Particle Molality= 2.0000 mol/kg
- 6Molality Needed for a One-Degree Rise= 0.9766 mol/kg
- 7Interpretation= Electrolyte — dissociation multiplies the effect
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Boiling Point Elevation calculated?
ΔT_b = i K_b b, with i the van’t Hoff factor Boiling point elevation is a colligative property, depending only on particle count rather than identity. Electrolytes dissociate, so the van’t Hoff factor multiplies the effect.
Why does Boiling Point Elevation matter?
The effect is small: even 1 molal salt raises water’s boiling point by only about one degree, which is why salting pasta water is about flavour rather than cooking speed.
What values do I need to enter?
This calculator takes 4 inputs: Molality of the solution, Ebullioscopic constant, Van’t Hoff factor, Normal boiling point. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.