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 helps chemists and engineers estimate the vapor pressure of liquids at various temperatures.

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 logarithm of vapor pressure to the reciprocal of temperature.

3. Importance of Vapor Pressure Calculation

Details: Vapor pressure is crucial for designing distillation systems, predicting evaporation rates, and understanding phase equilibria.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: Where can I find Antoine constants for other substances?
A: Chemical engineering handbooks and databases like NIST provide Antoine constants for many compounds.

Q2: What's the temperature range validity for the Antoine equation?
A: The equation is typically valid within ±50°C of the boiling point. Constants are different above/below this range.

Q3: Why does the equation use base-10 logarithm?
A: The original Antoine equation was formulated with base-10 logs for practical calculation purposes.

Q4: Can I use this for mixtures?
A: No, the Antoine equation is for pure substances. For mixtures, use Raoult's Law or other methods.

Q5: How accurate is the Antoine equation?
A: Typically within 1-5% for most substances within their valid temperature ranges.