Vapor Pressure Calculator
Calculate vapor pressure using Clausius-Clapeyron equation and Raoult's law
Calculate Vapor Pressure
Energy required to vaporize one mole of substance
Vapor Pressure Results
Clausius-Clapeyron Equation: ln(P₂/P₁) = (ΔH/R) × (1/T₁ - 1/T₂)
Method: Finding pressure at different temperature
Enthalpy Used: 40660 J/mol
Example Calculations
Water Vapor Pressure
Find vapor pressure of water at 80°C
Ethanol Boiling Point
Find boiling point of ethanol at reduced pressure
Glucose Solution
Vapor pressure of glucose in water solution
Common Substances
Pressure Units
Key Concepts
Understanding Vapor Pressure
What is Vapor Pressure?
Vapor pressure is the pressure exerted by vapor molecules of a substance in a closed system at equilibrium. It occurs when molecules are both vaporizing and condensing at the same rate. Vapor pressure is directly related to molecular kinetic energy and intermolecular forces.
Key Factors
- •Temperature: Higher temperature increases vapor pressure
- •Molecular Weight: Lighter molecules have higher vapor pressure
- •Intermolecular Forces: Weaker forces lead to higher vapor pressure
Vapor Pressure Equations
Clausius-Clapeyron
ln(P₂/P₁) = (ΔH/R) × (1/T₁ - 1/T₂)
For pure substances
Relates pressure and temperature
Uses enthalpy of vaporization
Raoult's Law
P_solution = P_solvent × χ_solvent
For ideal solutions
Uses mole fractions
Predicts solution behavior
Practical Applications
Distillation
Separation of liquids based on different vapor pressures and boiling points.
Weather Prediction
Humidity and precipitation forecasting using water vapor pressure.
Food Preservation
Vacuum packaging and freeze-drying utilize vapor pressure principles.