Clausius–Clapeyron Equation Calculator
🔥 Thermochemistry & Bonding. Use the Clausius–Clapeyron equation formula to find vapour pressure at t₂, vapour pressure at t₁, enthalpy of vaporisation, t₂, t₁: pick the value you want, type the others, and the answer updates as you go.
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Vapour pressure at T₂ | kPa |
| Vapour pressure at T₁ | kPa |
| Enthalpy of vaporisation | kJ/mol |
| T₂ | K |
| T₁ | K |
Worked example
Find the vapour pressure at t₂ when Vapour pressure at T₁ = 47.3 kPa, Enthalpy of vaporisation = 40.7 kJ/mol, T₂ = 373 K, T₁ = 353 K.
Using 2/P1 = -Δ HvapR(1/T2 - 1/T1): Vapour pressure at T₂ = 99.49 kPa.
Frequently asked questions
What is the formula for Clausius–Clapeyron equation?
2/P1 = -Δ HvapR(1/T2 - 1/T1).
What do the letters stand for, and what units are used?
Vapour pressure at T₂ in kPa, Vapour pressure at T₁ in kPa, Enthalpy of vaporisation in kJ/mol, T₂ in K, T₁ in K.
How do you calculate vapour pressure at t₂?
Put the values into 2/P1 = -Δ HvapR(1/T2 - 1/T1). For example, with Vapour pressure at T₁ = 47.3 kPa, Enthalpy of vaporisation = 40.7 kJ/mol, T₂ = 373 K, T₁ = 353 K, vapour pressure at t₂ = 99.49 kPa.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (vapour pressure at t₂, vapour pressure at t₁, enthalpy of vaporisation, t₂, t₁) and fill in the others: it rearranges the formula for you.
