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 helps determine the vapor pressure of substances using the Antoine equation, which is widely used in chemical engineering and thermodynamics.

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 derived constants.

3. Importance of Vapor Pressure Calculation

Details: Vapor pressure is crucial for understanding evaporation rates, boiling points, and the behavior of substances in various conditions. It's essential in chemical process design, meteorology, and material science.

4. Using the Calculator

Tips: Enter the temperature in °C and the Antoine constants (A, B, C) for your specific substance. Default values are for water at 1-100°C range.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for A, B, C constants?
A: For water (1-100°C): A=8.07131, B=1730.63, C=233.426. Different substances have different constants.

Q2: What temperature range is valid for this equation?
A: The Antoine equation is typically valid for specific temperature ranges that vary by substance.

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

Q4: Can I use this for any substance?
A: Yes, but you must use the correct Antoine constants for your specific substance and temperature range.

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