1. What is Gibbs Free Energy?

Definition: Gibbs Free Energy is a thermodynamic potential that measures the maximum reversible work that may be performed by a thermodynamic system at constant temperature and pressure.

Purpose: It helps predict whether a process will occur spontaneously at constant pressure and temperature.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( G \) — Gibbs free energy (J)
• \( G^{ig} \) — Ideal gas Gibbs free energy (J)
• \( R \) — Universal gas constant (8.314 J/mol·K)
• \( T \) — Temperature (K)
• \( \phi \) — Fugacity coefficient (dimensionless)

Explanation: The formula accounts for deviations from ideal gas behavior through the fugacity coefficient.

3. Importance of Gibbs Free Energy

Details: Gibbs free energy is crucial for understanding chemical reactions, phase transitions, and other thermodynamic processes.

4. Using the Calculator

Tips: Enter the ideal gas Gibbs energy (J), temperature (K), and fugacity coefficient (φ). Temperature must be > 0K and φ > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the fugacity coefficient?
A: The fugacity coefficient (φ) is the ratio of fugacity to pressure, measuring deviation from ideal gas behavior (φ=1 for ideal gases).

Q2: What are typical values for φ?
A: For real gases, φ typically ranges from 0.5 to 1.5 depending on pressure and temperature.

Q3: How do I find G^ig?
A: G^ig can be calculated from standard Gibbs energies of formation or using statistical thermodynamics.

Q4: What units should I use?
A: Use joules (J) for energy, kelvin (K) for temperature, and φ is dimensionless.

Q5: When is this calculation most useful?
A: For real gas systems at high pressures or low temperatures where ideal gas assumptions break down.