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Enthalpy of Vaporisation from Two Temperature–Pressure Points Calculator

ΔH_vap from Clausius–Clapeyron using two (T, P) data points.

Solves the integrated Clausius–Clapeyron equation: ln(P₂/P₁) = −ΔH_vap/R × (1/T₂ − 1/T₁) for ΔH_vap in kJ/mol.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

kPa
K
kPa
K

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

ΔH_vap = R · ln(P₂/P₁) / (1/T₁ − 1/T₂)

In depth

Solves the integrated Clausius–Clapeyron equation: ln(P₂/P₁) = −ΔH_vap/R × (1/T₂ − 1/T₁) for ΔH_vap in kJ/mol.