Vapor Pressure Calculator

Calculate Vapor Pressure and Phase Equilibrium

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Antoine Equation Calculator

Calculate vapor pressure using the Antoine equation.

Vapor Pressure: - mmHg

Clausius-Clapeyron Calculator

Calculate vapor pressure change with temperature using the Clausius-Clapeyron equation.

Final Vapor Pressure: - mmHg

Water Vapor Pressure Calculator

Calculate water vapor pressure at different temperatures.

Water Vapor Pressure: - mmHg

Understanding Vapor Pressure

What is Vapor Pressure?

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid phase:

  • Measure of liquid's tendency to vaporize
  • Temperature dependent property
  • Key factor in distillation
  • Important for phase equilibria

Antoine Equation

The Antoine equation relates vapor pressure to temperature:

  • log₁₀(P) = A - B/(T + C)
  • Semi-empirical relationship
  • Constants specific to each substance
  • Valid over limited temperature range

Clausius-Clapeyron Equation

Describes pressure-temperature relationship:

  • Based on thermodynamic principles
  • Uses heat of vaporization
  • Assumes ideal gas behavior
  • Useful for extrapolation

Applications

Vapor pressure calculations are crucial for:

  • Distillation design
  • Chemical separation processes
  • Environmental science
  • Industrial safety
  • Material storage conditions

Essential Vapor Pressure Formulas

Antoine Equation

log₁₀(P) = A - B/(T + C)

Where P is vapor pressure, T is temperature

Clausius-Clapeyron

ln(P₂/P₁) = -(ΔHvap/R)(1/T₂ - 1/T₁)

Where ΔHvap is heat of vaporization

Relative Humidity

RH = (P/P*) × 100%

Where P* is saturation vapor pressure