Boiling Point Calculator
Boiling Point Elevation0.5120 °C
New Boiling Point100.5120 °C
This boiling point calculator estimates how much a dissolved solute raises the boiling temperature of a solvent — a colligative property called boiling point elevation. It multiplies the solvent’s ebullioscopic constant by the solution molality and the van’t Hoff factor, then adds the rise to water’s normal boiling point of 100 °C. The more dissolved particles per kilogram of solvent, the higher the boiling point climbs.
Formula
ΔTb = i · Kb · m; new boiling point = 100 °C + ΔTb
- ΔTb
- Boiling point elevation in °C
- i
- Van’t Hoff factor — particles produced per dissolved formula unit
- Kb
- Ebullioscopic constant of the solvent (°C·kg/mol)
- m
- Molality of the solution (mol solute per kg solvent)
How it works
- Enter the ebullioscopic (boiling-point-elevation) constant Kb of the solvent — for water it is about 0.512 °C·kg/mol.
- Enter the molality of the solution (moles of solute per kilogram of solvent) and the van’t Hoff factor i, which counts how many particles each formula unit splits into.
- The calculator multiplies i × Kb × molality to get the elevation, rounds it to four decimals, and adds it to 100 °C to report the new boiling point.
Worked example
A 1 molal solution of table salt (NaCl) in water, where Kb = 0.512 and i = 2.
- NaCl dissociates into Na⁺ and Cl⁻, so the van’t Hoff factor i = 2.
- Elevation: ΔTb = 2 × 0.512 × 1 = 1.024 °C.
- New boiling point: 100 + 1.024 = 101.024 °C.
The boiling point rises by 1.024 °C to 101.024 °C.
Frequently asked questions
- What is the van’t Hoff factor?
- It is the number of particles a solute splits into when dissolved. Non-electrolytes like sugar stay as one particle (i = 1), while NaCl separates into two ions (i = 2) and CaCl₂ into three (i = 3).
- Why does the calculator assume water with a base of 100 °C?
- It adds the elevation to the normal boiling point of water, 100 °C at sea level. The Kb value you enter is solvent-specific, but the displayed new boiling point is referenced to water’s 100 °C baseline.
- Does pressure or altitude affect this result?
- This model uses the sea-level boiling point of 100 °C and does not adjust for altitude or pressure. At higher altitudes the base boiling point is lower, so the absolute boiling temperature would shift down.
- Why is boiling point elevation a colligative property?
- Because it depends on the number of dissolved particles, not their chemical identity. One mole of any non-volatile solute particles raises the boiling point by the same amount in a given solvent.