1. What is Vapor Pressure?

Definition: Vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature.

Purpose: This calculator estimates vapor pressure using the Antoine equation, which is widely used in chemistry and chemical engineering.

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 of a substance to its temperature through empirically determined constants.

3. Importance of Vapor Pressure Calculation

Details: Vapor pressure is crucial for understanding evaporation rates, boiling points, and the volatility of substances. It's essential in chemical process design, environmental studies, and material safety.

4. Using the Calculator

Tips:

• Enter temperature in °C
• Default constants are for water (A=8.07131, B=1730.63, C=233.426)
• Use substance-specific constants for accurate results
• Temperature must be > -C to avoid division by zero

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for A, B, C constants?
A: For water: A=8.07131, B=1730.63, C=233.426. Other substances have different constants.

Q2: What's the temperature range for this equation?
A: The Antoine equation is typically valid for temperatures between a substance's melting and boiling points.

Q3: Why does the equation use base-10 logarithm?
A: The Antoine equation is empirical, and base-10 provides the best fit for experimental data.

Q4: Can I use this for any substance?
A: Yes, but you need the correct A, B, C constants for that specific substance.

Q5: How accurate is the Antoine equation?
A: It's very accurate within its valid temperature range for most substances.