1. What is the Vapor Pressure Formula?

Definition: The Antoine equation calculates the vapor pressure of a substance as a function of temperature.

Purpose: It's widely used in chemistry and chemical engineering to estimate vapor pressures of pure liquids.

2. How Does the Calculator Work?

The calculator uses the Antoine equation:

Where:

• \( P \) — Vapor pressure (mmHg)
• \( T \) — Temperature (°C)
• \( A, B, C \) — Substance-specific constants

Explanation: The equation relates the vapor pressure to temperature through empirically determined constants.

3. Importance of Vapor Pressure Calculation

Details: Vapor pressure is crucial for understanding evaporation rates, boiling points, and designing distillation systems.

4. Using the Calculator

Tips: Enter the temperature in °C and the Antoine constants (default values for water). The calculator will compute the vapor pressure in mmHg.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for A, B, C?
A: For water: A=8.07131, B=1730.63, C=233.426 (for 1-100°C range). Values differ for other substances.

Q2: What temperature range is valid?
A: The equation is valid only within the temperature range used to determine the constants.

Q3: Why mmHg units?
A: mmHg (millimeters of mercury) is a traditional pressure unit, but you can convert to other units if needed.

Q4: Can I use this for mixtures?
A: No, the Antoine equation is for pure substances. Mixtures require more complex calculations.

Q5: Where can I find Antoine constants?
A: Chemical engineering handbooks and databases like NIST provide constants for many substances.