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Boiling-Point Elevation Calculator.

Calculate colligative boiling-point elevation from molality, Kb, and van't Hoff factor.

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Boiling-point elevation: 1.024 K

Boiling-point elevation

1.024000K

Educational formula calculator. Keep units consistent; chemistry procedures, concentrations, and safety decisions require qualified laboratory guidance. Never mix cleaning products.

Use Cases

Determine boiling point of solutions

Use this calculator to find the boiling-point elevation for solutions in chemistry labs or industrial processes, helping to predict boiling temperatures.

Example: Calculate ΔTb for 0.5 mol/kg sucrose (i=1) in water (Kb=0.512): ΔTb = 0.256 K.

Verify colligative properties in experiments

Check experimental results by comparing measured boiling-point elevations with calculated values, ensuring accuracy in physical chemistry studies.

Example: If you measure ΔTb = 0.51 K for a 0.5 mol/kg NaCl solution, the calculator gives 0.512 K (i=2), confirming near-ideal behavior.

Frequently Asked Questions

What is boiling-point elevation?
Boiling-point elevation is a colligative property where the boiling point of a solvent increases when a solute is dissolved. It depends on the number of solute particles, not their identity. The formula is ΔTb = i * Kb * m, where i is the van't Hoff factor, Kb is the ebullioscopic constant, and m is molality.
How do I use this calculator?
Enter the molality of the solution (mol/kg), the van't Hoff factor (i), and the ebullioscopic constant (K·kg/mol) for your solvent. The calculator will compute the boiling-point elevation (ΔTb) in Kelvin. For example, for 1 mol/kg NaCl (i=2) in water (Kb=0.512), ΔTb = 1.024 K.
What is the van't Hoff factor?
The van't Hoff factor (i) represents the number of particles a solute dissociates into in solution. For non-electrolytes like sugar, i=1. For strong electrolytes like NaCl, i=2 (Na+ and Cl-). For weak electrolytes, i is between 1 and the theoretical maximum, depending on dissociation.

Tips & Common Mistakes

Tips

  • Ensure molality is in mol/kg, not molarity (mol/L), as the formula uses molality.
  • Use the correct ebullioscopic constant for your solvent (e.g., water: 0.512 K·kg/mol, benzene: 2.53 K·kg/mol).
  • For strong electrolytes, use the theoretical van't Hoff factor (e.g., NaCl: 2, CaCl2: 3) for ideal solutions.
  • Remember that the calculator gives the elevation (ΔTb), not the final boiling point. Add ΔTb to the pure solvent's boiling point to get the solution's boiling point.

Common Mistakes to Avoid

  • Using molarity instead of molality. Molality is moles of solute per kilogram of solvent, not per liter of solution.
  • Forgetting to include the van't Hoff factor for ionic compounds, leading to underestimated ΔTb.
  • Using the wrong ebullioscopic constant for the solvent, which gives incorrect results.

Last updated: August 13, 2026