Clausius-Clapeyron Equation

The Clausius-Clapeyron Equation for Pressure calculator estimates the vapor pressure of a liquid at a certain temperature when the vapor pressure at another temperature is known. 

INSTRUCTIONS: Choose units and enter the following:

• (P₁) Vapor Pressure 1
• (ΔH_vap)  Molar Enthalpy of Vaporization
• (T₁)  Temperature 1 (corresponds with P₁)
• (T₂) Temperature 2 

Pressure (P₂): The calculator returns the vapor pressure at temperature T₂ in atmospheres.  However, the pressure can be automatically converted to other pressure units (.e.g., pascals) via the pull-down menu. 

The Math

The Clausius-Clapeyron Equation is as follows:

     `ln((P_1)/(P_2)) = -(DeltaH_(vap))/R * (1/T_1  - 1/T_2)`  

where R is the ideal gas constant (8.314 J/mol*K)

This calculator solves the above equation for P₂.  Therefore, the Clausius-Clapeyron equation for final pressure is:

     `P_2 = P_1 * e^((DeltaH_"vap")/R (1/T_1 - 1/T_2))`

where:

• P₂ = Pressure at T₂
• P₁ = Pressure at T₁
• T₁ = Temperature 1
• T₂ = Temperature 2
• R = Ideal Gas Constant

Clausius-Clapeyron Equation Calculators

• Clausius-Clapeyron Pressure
• Clausius-Clapeyron Temperature

Chemistry Calculators

• R - Gas Constant: 8.3144626181532 J/(K⋅mol)
• Boyle's Law Calculator:  P₁ • V₁ = P₂ • V₂
• Charles Law Calculator: V₁• T₂ = V₂ • T₁
• Combined Gas Law Calculator:   P•V / T= k
• Gay-Lussac Law:  T₁•P₂ =T₂•P₁ 
• Ideal Gas Law: P•V = n•R•T
• Bragg's Law:   n·λ = 2d·sinθ
• Hess' Law:  ΔH⁰_rxn=ΔH⁰_a+ΔH⁰_b+ΔH⁰_c+ΔH⁰_d
• Internal Energy: ΔU = q + ω 
• Activation Energy:  E_a = (R*T₁⋅T₂)/(T₁ - T₂) ⋅  ln(k₁/k₂)
• Arrhenius Equation:  k = Ae^E_a/(RT)
• Clausius-Clapeyron Equation:  ln(P₂/P₁) = (ΔH_vap)/R * (1/T₁ - 1/T₂)
• Compressibility Factor: Z = (p*V_m)/(R*T)
• Peng-Robinson Equation of State:  p = (R*T)/(V_m - b) - (a*α)/(V_m² + 2*b*V_m - b²)
• Reduced Specific Volume:  v_r = v/(R* T_cr / P_c)
• Van't Hoff Equation:  ΔH⁰ = R * ( -ln(K₂/K₁))/ (1/T₁ - 1/T₂)

Supplemental Materials

UCDavis ChemWiki: Clausius-Clapeyron Equation

YouTube: Find the Vapour Pressure (Clausius-Clapeyron Equation)

References

Whitten, et al. "Chemistry" 10th Edition. Pp. 467