1. What is a Water Vapour Pressure Calculator?

Definition: This calculator estimates the vapour pressure of water based on temperature using the Antoine equation.

Purpose: It helps scientists, engineers, and students determine the pressure exerted by water vapour at a given temperature.

2. How Does the Calculator Work?

The calculator uses the Antoine equation:

Where:

• \( P \) — Vapour pressure (mmHg)
• \( T \) — Temperature (°C)

Explanation: This empirical relationship describes how water vapour pressure changes with temperature.

3. Importance of Vapour Pressure Calculation

Details: Knowing water vapour pressure is essential for humidity control, chemical engineering processes, meteorology, and HVAC system design.

4. Using the Calculator

Tips: Enter the temperature in degrees Celsius. The valid range is typically between -100°C and 200°C.

5. Frequently Asked Questions (FAQ)

Q1: What is the Antoine equation?
A: It's a semi-empirical relationship between vapour pressure and temperature for pure substances.

Q2: Why is vapour pressure important?
A: It affects evaporation rates, boiling points, and is crucial for understanding phase equilibria.

Q3: How accurate is this calculation?
A: Very accurate for liquid water between 1°C and 100°C, with decreasing accuracy outside this range.

Q4: What units does this calculator use?
A: Temperature in °C and vapour pressure in mmHg (millimeters of mercury).

Q5: Can I use this for other liquids?
A: No, this specific equation is only for water. Other substances have different Antoine coefficients.