Peng-Robinson Equation:
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Definition: The Peng-Robinson equation is a thermodynamic equation of state used to describe the behavior of real gases.
Purpose: It provides more accurate pressure predictions than the ideal gas law, especially near the critical point.
The calculator uses the Peng-Robinson equation:
Where:
Details: This equation is widely used in chemical engineering and petroleum industries for modeling hydrocarbon systems and other non-ideal gases.
Tips: Enter all required parameters. Temperature and molar volume must be positive values. Parameters a, b, and α are typically determined from experimental data or correlations.
Q1: What's the difference between ideal gas law and Peng-Robinson?
A: Peng-Robinson accounts for molecular size and intermolecular forces, making it more accurate for real gases.
Q2: How do I determine parameters a and b?
A: They are typically calculated from critical properties (Tc, Pc) and the acentric factor (ω) of the substance.
Q3: What is the α-function?
A: It's a temperature-dependent function that modifies the attractive term in the equation.
Q4: What units should I use?
A: Use Kelvin for temperature, m³/mol for molar volume, and consistent units for parameters a and b.
Q5: When is this equation most accurate?
A: It works well for non-polar and slightly polar compounds, especially hydrocarbons.