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Boiling Point Elevation Calculator

Calculate Boiling Point Elevation

Find Molality from Elevation

Molar Mass from Boiling Point

Determine molar mass of unknown solute from BP elevation

Formula

ΔTb = i × Kb × m | New BP = Normal BP + ΔTb | Kb(water) = 0.512 °C·kg/mol

Frequently Asked Questions

What is boiling point elevation?
Boiling point elevation is the increase in boiling point when a non-volatile solute is added to a solvent. ΔTb = i·Kb·m, where Kb is the ebullioscopic constant, m is molality, and i is the van't Hoff factor. It is a colligative property.
Why does adding salt raise the boiling point of water?
Salt (NaCl, i=2) dissolves and reduces the solvent's vapor pressure (Raoult's Law). A higher temperature is needed to reach the atmospheric pressure and boil. For 1 m NaCl in water: ΔTb = 2 × 0.512 × 1 = 1.024°C.
What is the ebullioscopic constant?
Kb is specific to each solvent: Water = 0.512°C·kg/mol, Benzene = 2.53, Chloroform = 3.63. It depends on the solvent's molar mass, boiling point, and enthalpy of vaporization.

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