Formula Used:
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Definition: Residual Gibbs Free Energy is the difference between the Gibbs energy of a real system and that of an ideal system at the same temperature and pressure.
Purpose: It quantifies the deviation from ideal behavior in thermodynamic systems and is crucial for understanding real gas behavior and phase equilibria.
The calculator uses the formula:
Where:
Explanation: The natural logarithm of the fugacity-pressure ratio is multiplied by temperature and the gas constant to calculate the residual Gibbs energy.
Details: This calculation is essential for chemical engineering thermodynamics, particularly in process design, phase equilibrium calculations, and non-ideal system analysis.
Tips: Enter temperature in Kelvin, fugacity and pressure in Pascals. All values must be positive numbers.
Q1: What is fugacity?
A: Fugacity is a thermodynamic property that represents the "effective pressure" of a real gas, accounting for non-ideal behavior.
Q2: When is residual Gibbs energy positive vs negative?
A: Positive when f > P (repulsive interactions dominate), negative when f < P (attractive interactions dominate).
Q3: What units should I use?
A: Temperature in Kelvin, fugacity and pressure in Pascals. The result is in Joules.
Q4: Can I use this for liquid phases?
A: Yes, the concept applies to any phase, but ensure you have accurate fugacity data for liquids.
Q5: How does temperature affect the result?
A: Higher temperatures amplify the effect of non-ideality (larger absolute GR values for same f/P ratio).