1. What is Vapor Pressure Calculation?

Definition: This calculator estimates the vapor pressure of a liquid at a given temperature using the Clausius-Clapeyron equation.

Purpose: It helps chemists, engineers, and researchers predict how a liquid's vapor pressure changes with temperature.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P \) — Vapor pressure at temperature T (Pa)
• \( P_0 \) — Reference vapor pressure (typically at boiling point, 101325 Pa)
• \( \Delta H \) — Enthalpy of vaporization (J/mol)
• \( R \) — Universal gas constant (8.314 J/mol·K)
• \( T \) — Temperature of interest (K)
• \( T_0 \) — Reference temperature (boiling point in K)

Explanation: The equation relates the vapor pressures at two temperatures to the enthalpy of vaporization.

3. Importance of Vapor Pressure Calculation

Details: Vapor pressure determines evaporation rates, boiling points, and is crucial for distillation, drying processes, and environmental modeling.

4. Using the Calculator

Tips: Enter the reference pressure (P₀), enthalpy of vaporization (ΔH), temperature (T), and reference temperature (T₀). Default values are for water (P₀=101325 Pa at boiling point, ΔH=40660 J/mol, T₀=373K).

5. Frequently Asked Questions (FAQ)

Q1: What is the reference pressure P₀?
A: This is typically the vapor pressure at the boiling point (101325 Pa or 1 atm for water at 100°C).

Q2: How do I find the enthalpy of vaporization?
A: It's often tabulated in chemistry handbooks (40660 J/mol for water at boiling point).

Q3: What units should I use for temperature?
A: Always use Kelvin (K) for temperature in this calculation.

Q4: Can I use this for any liquid?
A: Yes, but you need the correct P₀, ΔH, and T₀ values for that specific substance.

Q5: Why does the result have many decimal places?
A: Vapor pressure calculations are sensitive to small changes, so precision is important.