What is the van't Hoff factor (i)?

The van't Hoff factor accounts for the number of particles a solute produces when dissolved. Non-electrolytes like glucose have i = 1. Strong electrolytes split into ions: NaCl → 2 ions (i = 2), CaCl2 → 3 ions (i = 3), etc.

What is molality and how is it different from molarity?

Molality (m) is moles of solute per kilogram of solvent, while molarity (M) is moles of solute per liter of solution. Molality is used for colligative properties because it is independent of temperature.

Why does dissolving a solute raise the boiling point?

Solute particles lower the vapor pressure of the solvent (Raoult's Law). A lower vapor pressure means the solution must be heated to a higher temperature before its vapor pressure equals atmospheric pressure, raising the boiling point.

What is the Kb (ebullioscopic constant)?

Kb is a solvent-specific constant that represents the boiling point rise per molal concentration of a non-dissociating solute. Water has Kb = 0.512 °C·kg/mol; benzene has Kb = 2.53 °C·kg/mol.

Can I use this for real-world antifreeze calculations?

Yes. Ethylene glycol in water is a classic example. Use i = 1 (it does not dissociate), the molality of glycol, and water's Kb of 0.512 to estimate the boiling point rise of your coolant mixture.

Boiling Point Elevation Calculator

Name: Boiling Point Elevation Calculator
Availability: InStock
Author: Nham Vu

Calculate how much a solute raises a solvent's boiling point using ΔTb = Kb × m × i.

Common Solvents — Click to Use

Solvent	Kb (°C·kg/mol)	BP (°C)

Enter Values

Kb — Ebullioscopic Constant (°C·kg/mol)

Molality, m (mol/kg)

Van't Hoff Factor, i

Fill in the values and click Calculate

Van't Hoff Factor Reference

Compound	Dissociation	i (ideal)
Glucose, Sucrose, Urea	No dissociation	1
NaCl, KCl, HCl	→ 2 ions	2
CaCl2, MgCl2, Na2SO4	→ 3 ions	3
AlCl3, FeCl3	→ 4 ions	4

Click a row to auto-fill the van't Hoff factor.

Summary

Calculate how much a solute raises a solvent's boiling point using ΔTb = Kb × m × i.

How it works

Select a solvent from the reference table or enter a custom Kb value.
Enter the molality (mol of solute per kg of solvent).
Enter the van't Hoff factor i (1 for non-electrolytes, 2 for NaCl, 3 for CaCl2, etc.).
The calculator applies ΔTb = Kb × m × i to find the elevation.
The new boiling point is shown as the solvent's normal boiling point plus ΔTb.

Use cases

Chemistry students calculating boiling point elevation for lab reports.
Determining the boiling point of saltwater or sugar solutions.
Comparing how different solvents respond to the same solute concentration.
Understanding how ionic compounds (i > 1) raise the boiling point more than molecular solutes.
Verifying experimental results against the theoretical ΔTb formula.
Teaching colligative properties in general chemistry courses.

Frequently Asked Questions

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Last updated: 2026-05-28 · Reviewed by Nham Vu