1. What is Second Virial Coefficient?

Definition: The second virial coefficient (B₁₁) describes the contribution of the pair-wise potential of component 1 with itself to the pressure of the gas.

Purpose: It helps in understanding non-ideal gas behavior and is used in equations of state to predict real gas properties.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( B_{11} \) — Second virial coefficient (m³)
• \( \phi_1^{sat} \) — Saturated fugacity coefficient of component 1 (dimensionless)
• \( R \) — Universal gas constant (8.314 J/mol·K)
• \( T_{VLE} \) — Temperature of liquid-vapor system (K)
• \( P_1^{sat} \) — Saturated pressure of component 1 (Pa)

Explanation: The natural log of the fugacity coefficient is multiplied by the gas constant and temperature, then divided by the saturated pressure.

3. Importance of Second Virial Coefficient

Details: This coefficient is crucial for accurate thermodynamic calculations, particularly in phase equilibrium studies and gas property predictions.

4. Using the Calculator

Tips: Enter the saturated fugacity coefficient (must be > 0), temperature in Kelvin (must be > 0), and saturated pressure in Pascals (must be > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is the physical significance of B₁₁?
A: It represents the deviation from ideal gas behavior due to interactions between pairs of molecules of component 1.

Q2: What's a typical range for B₁₁?
A: Values are typically small (order of 10^-5 to 10^-3 m³/mol) and can be positive or negative depending on temperature.

Q3: How does temperature affect B₁₁?
A: B₁₁ generally increases with temperature, starting negative at low temperatures and becoming positive at higher temperatures.

Q4: What is the fugacity coefficient?
A: It's a measure of non-ideality, representing the ratio of a component's fugacity to its pressure.

Q5: When would I need to calculate B₁₁?
A: When working with real gas mixtures, designing chemical processes, or modeling phase equilibria.