Calculate boiling-point elevation, freezing-point depression, or a rough water boiling-point shift with pressure.
| ΔT (°C) | – |
Use this calculator in lab or field when you dissolved a solute and want ΔT, or you are at altitude and want how much water’s boiling point moves.
For boiling elevation and freezing depression: ΔT = K × i × molality. Type Kb or Kf as K; i is 1 for sugar and about 2 for NaCl if fully dissociated. In altitude mode K and i are unused: type pressure in kPa in the molality box. The rough troposphere fit is ΔT = 100 × (P / 101.325)^0.28 − 100, so sea-level pressure gives ΔT = 0.
Mode: Boiling elevation or freezing depression for a solution, or boil versus pressure for altitude.
Kb, Kf, or unused: Kb or Kf in °C·kg/mol. Water is about 0.512 (boil) or 1.86 (freeze). Unused in altitude mode.
Molality (or P kPa): Molality in mol/kg solvent, or pressure in kPa if you picked altitude (sea level ≈ 101.3).
van ’t Hoff i: van ’t Hoff factor. 1 for nonelectrolytes, about 2 for NaCl. Unused in altitude mode.
ΔT (°C): Temperature shift in °C (rise for boiling, drop for freezing, or boil-point change versus 100 °C).
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