Science & Lab Tools
Boiling Point Elevation Calculator
Calculate how dissolved solutes increase the boiling point of a solution
Reviewed by the calculator.uk.com Team · Last reviewed 7 June 2026 · Our methodology
Enter values to calculate boiling point elevation
Related to Boiling Point Elevation Calculator
The Boiling Point Elevation Calculator determines how much the boiling point of a solvent increases when a non-volatile solute is dissolved in it. This phenomenon, known as boiling point elevation, is a colligative property that depends on the number of dissolved particles rather than their chemical nature.
The Formula
ΔTb = Kb × m
Where:
ΔTb = Boiling point elevation (°C)
Kb = Ebullioscopic constant (°C⋅kg/mol)
m = Molality of solution (mol solute/kg solvent)
The calculator first determines the molality of the solution by dividing the number of moles of solute by the mass of solvent in kilograms. Then, it multiplies this value by the solvent's ebullioscopic constant (Kb) to find the boiling point elevation. The new boiling point is calculated by adding this elevation to the solvent's normal boiling point.
The calculator provides three key pieces of information to help you understand how the solute affects the solvent's boiling point:
Solution Molality
Expressed in mol/kg, this value indicates the concentration of the solution. Higher molality means more solute particles per kilogram of solvent, resulting in a greater boiling point elevation.
Boiling Point Elevation
This is the increase in boiling point (ΔTb) in degrees Celsius. A larger elevation indicates a stronger effect of the solute on the solvent's boiling point.
New Boiling Point
The final boiling point of the solution, calculated by adding the elevation to the solvent's normal boiling point. This is the temperature at which the solution will boil at standard atmospheric pressure.
1. What is boiling point elevation?
Boiling point elevation is a colligative property where the boiling point of a liquid increases when a non-volatile solute is dissolved in it. This happens because the solute particles interfere with the solvent's ability to escape into the vapor phase, requiring more energy (higher temperature) for boiling to occur.
2. What is the ebullioscopic constant (Kb)?
The ebullioscopic constant (Kb) is a property specific to each solvent that indicates how much its boiling point will increase per unit of molal concentration. It's measured in °C⋅kg/mol and is determined by the solvent's physical properties.
3. Why do different solvents have different Kb values?
Different solvents have different Kb values because of variations in their intermolecular forces, vapor pressure characteristics, and molar heat of vaporization. Solvents with stronger intermolecular forces typically have higher Kb values.
4. What are some practical applications of boiling point elevation?
Boiling point elevation has many practical applications, including: antifreeze in car radiators, cooking (adding salt to boiling water), preventing freezing of roads with salt, and industrial processes where specific boiling points are needed. It's also used in determining molecular weights of unknown compounds.
5. What is the scientific source for this calculator?
Boiling point elevation is one of the four classical colligative properties, following from Raoult's law and the reduction in solvent vapor pressure that dissolved solute particles cause. The ebullioscopic constant (Kb) is solvent-specific, and the values used here match standard tabulated figures such as those in the CRC Handbook of Chemistry and Physics. The governing relationship, ΔTb = i·Kb·m, is core physical chemistry covered in texts like Atkins' Physical Chemistry.