1. What is Van der Waals Constant a?

Definition: The Van der Waals Constant a accounts for the intermolecular attractive forces between gas molecules.

Purpose: It's used in the Van der Waals equation to correct the ideal gas law for real gas behavior.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( a \) — Van der Waals constant (Pa·m⁶/mol²)
• \( P_c \) — Critical pressure (Pascal)
• \( b \) — Van der Waals constant b (m³/mol)

Explanation: The formula relates the intermolecular forces constant to the critical pressure and molecular volume constant.

3. Importance of Van der Waals Constants

Details: These constants are essential for accurate modeling of real gas behavior, especially under high pressure or low temperature conditions.

4. Using the Calculator

Tips: Enter the critical pressure in Pascals and Van der Waals constant b in m³/mol. Both values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for Van der Waals constant a?
A: Values vary by gas. For example: Water ≈ 0.5537 Pa·m⁶/mol², Nitrogen ≈ 0.1408 Pa·m⁶/mol².

Q2: How is critical pressure determined?
A: It's measured experimentally as the pressure required to liquefy a gas at its critical temperature.

Q3: What's the physical meaning of constant b?
A: It represents the volume occupied by one mole of gas molecules (excluded volume).

Q4: Can I calculate b if I know a?
A: Yes, you can rearrange the formula: \( b = \sqrt{a/(27 \times P_c)} \).

Q5: Why is the factor 27 in the formula?
A: It comes from the derivation of critical constants from the Van der Waals equation.