1. What is a Vapor Pressure Calculator?

Definition: This calculator estimates the vapor pressure of a substance using the Antoine equation, which relates vapor pressure to temperature.

Purpose: It helps chemists, engineers, and students determine 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 calculates the base-10 logarithm of vapor pressure as a function of temperature and three empirical 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.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

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

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

Q3: Why does the equation use base-10 logarithm?
A: The Antoine equation was originally formulated this way for computational convenience.

Q4: How accurate is this calculation?
A: Very accurate within the temperature range the constants were derived for.

Q5: Where can I find Antoine constants for other substances?
A: Chemical engineering handbooks and databases typically provide these values.