Fugacity Formula:
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Definition: Fugacity is a thermodynamic property that effectively represents the "escaping tendency" of a component from a phase. For liquid phase species, it's calculated considering saturation conditions and pressure effects.
Purpose: This calculator determines the fugacity of a species in the liquid phase using the Poynting factor correction, which accounts for pressure effects beyond saturation conditions.
The calculator uses the formula:
Where:
Explanation: The fugacity at saturation conditions (φsat × Psat) is corrected for pressure effects using the Poynting factor.
Details: Fugacity is crucial in phase equilibrium calculations, chemical reaction equilibria, and thermodynamic modeling of mixtures. Accurate fugacity values ensure proper design of separation processes and chemical reactors.
Tips: Enter the saturated fugacity coefficient (typically between 0 and 1), saturated pressure in Pascals, and the Poynting factor (usually close to 1 for moderate pressures). All values must be positive.
Q1: What is the Poynting factor?
A: The Poynting factor accounts for the effect of pressure on fugacity beyond the saturation pressure, correcting for how the chemical potential changes with pressure at constant temperature.
Q2: When is the Poynting factor significant?
A: The Poynting correction becomes important at high pressures or when precise fugacity calculations are needed. At low pressures, it's often close to 1.
Q3: How do I determine the saturated fugacity coefficient?
A: φsat can be calculated from equations of state or obtained from thermodynamic tables for pure components at saturation conditions.
Q4: What units should I use for pressure?
A: The calculator uses Pascals (Pa) for consistency with SI units. 1 bar = 100,000 Pa, 1 atm = 101,325 Pa.
Q5: Can this be used for mixtures?
A: This calculates pure component fugacity. For mixtures, additional terms for activity coefficients or mixture fugacity coefficients would be needed.