1. What is the Antoine Equation?

Definition: The Antoine equation is a semi-empirical relationship between vapor pressure and temperature for pure substances.

Purpose: It's widely used in chemical engineering and thermodynamics to estimate the vapor pressure of liquids at various temperatures.

2. How Does the Antoine Equation Work?

The equation uses the formula:

Where:

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

Explanation: The equation relates the logarithm of vapor pressure to the reciprocal of temperature, with constants that are empirically determined for each substance.

3. Importance of Vapor Pressure Calculation

Details: Vapor pressure is crucial for designing distillation columns, predicting evaporation rates, and understanding phase equilibrium in chemical processes.

4. Using the Calculator

Tips: Enter the temperature in °C and the Antoine constants (A, B, C) for your specific substance. Common values are provided as defaults.

5. Frequently Asked Questions (FAQ)

Q1: What are typical Antoine constants for water?
A: For water between 1-100°C: A=8.07131, B=1730.63, C=233.426 (these are the default values in the calculator).

Q2: What temperature range is valid for the Antoine equation?
A: The equation is typically valid over a limited temperature range (usually the normal boiling point ±50°C).

Q3: Where can I find Antoine constants for other substances?
A: Chemical engineering handbooks or databases like NIST Chemistry WebBook contain extensive tables of Antoine constants.

Q4: Why does the equation use base-10 logarithm?
A: The original Antoine equation was formulated with base-10 logs, though some modern variations use natural logarithms.

Q5: How accurate is the Antoine equation?
A: It's accurate to within a few percent for most substances within their valid temperature ranges.