Enter your Solvent Type, Ebullioscopic Constant (Kᵦ), van't Hoff Factor (i), and Molality (m) — or let the calculator find molality from your Solute Mass — to get the Boiling Point Elevation (ΔTᵦ) and your solution's New Boiling Point, showing exactly how much higher your solvent will boil once that solute is dissolved.
Boiling Point Elevation (ΔTᵦ)
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New Boiling Point
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Calculated Molality
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Boiling point elevation is the increase in boiling temperature that occurs when a non-volatile solute is dissolved in a solvent. This happens because the solute particles interfere with the solvent's ability to vaporize, requiring a higher temperature to reach the boiling point.
Boiling point elevation is calculated using the formula ΔTᵦ = i·Kᵦ·m, where ΔTᵦ is the temperature change, i is the van't Hoff factor, Kᵦ is the ebullioscopic constant of the solvent, and m is the molality of the solution.
The van't Hoff factor represents the number of particles a solute forms when dissolved. For non-electrolytes like sugar, i = 1. For electrolytes like NaCl, i = 2 (Na⁺ + Cl⁻). For CaCl₂, i = 3 (Ca²⁺ + 2Cl⁻).
The ebullioscopic constant (Kᵦ) of water is 0.512 °C·kg/mol. This means that a 1 molal solution of a non-electrolyte in water will have its boiling point elevated by 0.512 °C.
Molality (m) is moles of solute per kilogram of solvent, while molarity is moles of solute per liter of solution. Molality is used in colligative property calculations because it doesn't change with temperature, unlike molarity which can vary as solution volume changes.
Salt (NaCl) dissociates into Na⁺ and Cl⁻ ions in water, effectively doubling the number of particles. These particles lower the water's vapor pressure, requiring more heat energy to reach the vapor pressure needed for boiling, thus raising the boiling point.
Chloroform has one of the highest ebullioscopic constants at 3.63 °C·kg/mol, followed by acetic acid at 3.07 °C·kg/mol and benzene at 2.53 °C·kg/mol. Water has a relatively low Kᵦ of 0.512 °C·kg/mol.