water vapor pressure calculator

Calculate Vapor Pressure

About Vapor Pressure

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid phase. It's a fundamental property that depends on temperature and the nature of the substance.

Antoine Equation:

log₁₀(P) = A - B/(C + T)

Clausius-Clapeyron:

ln(P/P₀) = -(ΔH_vap/R) × (1/T - 1/T₀)

Raoult's Law:

P = x × P°

Where:

  • P = Vapor pressure
  • T = Temperature (°C)
  • A, B, C = Antoine constants
  • ΔH_vap = Enthalpy of vaporization
  • x = Mole fraction

Factors Affecting Vapor Pressure:

• Temperature (exponential relationship)
• Intermolecular forces
• Molecular size
• Surface area

Applications:

• Distillation design
• Evaporation processes
• Atmospheric science
• Chemical engineering

Understanding vapor pressure is essential for process design, environmental modeling, and predicting phase behavior.

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