What is the Clausius-Clapeyron equation?
The Clausius-Clapeyron equation relates vapor pressure to temperature using the enthalpy of vaporization. It's expressed as ln(P₂/P₁) = -ΔHvap/R × (1/T₂ - 1/T₁), where R is the gas constant.
What is the enthalpy of vaporization?
The enthalpy of vaporization (ΔHvap) is the energy required to convert one mole of liquid into vapor at constant temperature and pressure. It's typically expressed in kJ/mol and varies by substance.
How does temperature affect vapor pressure?
Vapor pressure increases exponentially with temperature. As temperature rises, more molecules have sufficient kinetic energy to escape the liquid phase, resulting in higher vapor pressure.
What is the Antoine equation?
The Antoine equation is an empirical formula that relates vapor pressure to temperature: log₁₀(P) = A - B/(C + T). Constants A, B, and C are substance-specific and valid only within certain temperature ranges.
How do I calculate boiling point from vapor pressure?
A liquid boils when its vapor pressure equals atmospheric pressure (760 mmHg at sea level). You can use either equation to find the temperature where vapor pressure equals 1 atmosphere.
Which method should I use - Clausius-Clapeyron or Antoine?
Use Clausius-Clapeyron when you have enthalpy of vaporization data and need thermodynamically accurate results. Use Antoine equation when you have the empirical constants and need high accuracy within the valid temperature range.