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Boiling Point Elevation

What Boiling Point Elevation Is and How It Works

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Adding salt to water increases its boiling point.

Adding salt to water increases its boiling point.

Markus Schweiss

Boiling point elevation occurs when the boiling point of a solution becomes higher than the boiling point of a pure solvent. The temperature at which the solvent boils is increased by adding any non-volatile solute. A common example of boiling point elevation can be observed by adding salt to water. The boiling point of the water is increased.

Boiling point elevation, like freezing point depression, is a colligative property of matter. This means it depends on the number of particles present in a solution and not on the type of particles or their mass.

The amount of boiling point elevation can be calculated using the Clausius-Clapeyron equation and Raoult's law. For an ideal dilute solution:

Boiling Pointtotal = Boiling Pointsolvent + ΔTb

where ΔTb = molality * Kb * i

with Kb = ebullioscopic constant (0.52°C kg/mol for water) and i = Van't Hoff factor

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