Vapor Pressure Calculator
Clausius-Clapeyron (Find P2)
Calculate vapor pressure at a new temperature
Find ΔHvap
Calculate heat of vaporization from two P-T data points
Raoult's Law
Vapor pressure of solution (ideal solution)
Formula
ln(P₂/P₁) = (ΔHvap/R)(1/T₁ - 1/T₂) | Raoult's: P = x × P° | R = 8.314 J/(mol·K)
Frequently Asked Questions
What is the Clausius-Clapeyron equation?
ln(P2/P1) = (ΔHvap/R)(1/T1 - 1/T2). It relates vapor pressure to temperature using the enthalpy of vaporization. P1 and P2 are vapor pressures at temperatures T1 and T2 (in Kelvin), R = 8.314 J/(mol·K).
What is Raoult's Law?
Raoult's Law states: P_solution = x_solvent × P°_solvent, where x is the mole fraction. Adding a non-volatile solute lowers the vapor pressure. This is a colligative property.
What affects vapor pressure?
Vapor pressure increases with temperature (exponentially). Stronger intermolecular forces = lower vapor pressure. Adding non-volatile solute decreases vapor pressure (Raoult's Law).
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