# Boiling Point Elevation

ΔT_b = K_b·m·i from a solvent preset table with van't Hoff factor support and custom solvents.

> Canonical page: https://elysiatools.com/en/tools/boiling-point-elevation

- **Category:** Science & Education

- **Keywords:** boiling point elevation, colligative property, ebullioscopy, molality, kb, van't hoff factor

## Overview

Calculate the colligative boiling point elevation (ΔT_b = K_b · m · i) of solutions using preset solvent constants or custom ebullioscopic values. The tool computes temperature changes and final solution boiling points for electrolytes and non-electrolytes alike.

## Inputs

- **Solvent** (select)
- **Custom K_b (K·kg/mol, overrides preset)** (number): e.g. 3.07 for acetic acid
- **Custom normal boiling point (°C)** (number): e.g. 118.1 for acetic acid
- **Molality m (mol solute per kg solvent)** (number): e.g. 0.5
- **van't Hoff factor i (particles per formula unit)** (number): 1 for sugar, 2 for NaCl, 3 for CaCl₂

## When to use

- Determining the elevated boiling point of an aqueous salt solution in chemistry coursework or laboratory prep.
- Evaluating ebullioscopic constants and temperature shifts for organic solvents like benzene, chloroform, or camphor.
- Analyzing the dissociation impact of ionic versus non-electrolyte solutes using the van 't Hoff factor.

## How it works

- Choose a preset solvent (such as water, benzene, ethanol, chloroform, carbon tetrachloride, or camphor) or select 'Custom' to provide your own K_b and normal boiling point.
- Enter the solution molality (m) in moles of solute per kilogram of solvent.
- Specify the van 't Hoff factor (i) corresponding to the number of dissociated particles per formula unit.
- The tool applies ΔT_b = K_b · m · i and adds ΔT_b to the solvent's normal boiling point to produce the final boiling point.

## Use cases

- Verifying colligative property problem sets for physical chemistry and general science courses.
- Predicting solvent boiling shifts during chemical synthesis and reflux setups.
- Comparing ebullioscopic sensitivity across solvents with varying K_b constants.

## Frequently asked questions

### What is the boiling point elevation formula?

It is ΔT_b = K_b · m · i, where K_b is the ebullioscopic constant, m is molality, and i is the van 't Hoff factor.

### What value should I use for the van 't Hoff factor (i)?

Use i = 1 for non-dissociating solutes like sucrose, i = 2 for binary electrolytes like NaCl, and i = 3 for salts like CaCl₂.

### How do I calculate boiling points for unlisted solvents?

Select the 'Custom solvent' option and manually input the solvent's K_b (in K·kg/mol) and normal boiling point in °C.

### Why is molality used instead of molarity?

Molality depends on solvent mass rather than volume, ensuring values remain constant regardless of temperature changes.

### Can I override a preset solvent's K_b value?

Yes, entering values into the Custom K_b and Custom normal boiling point fields overrides the standard preset values.

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