Critical Pressure Formula:
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Definition: Critical pressure is the minimum pressure required to liquefy a substance at its critical temperature.
Purpose: This calculator determines the critical pressure using the Peng-Robinson equation of state, which provides more accurate results for real gases compared to ideal gas laws.
The calculator uses the Peng-Robinson equation:
Where:
Details: Accurate critical pressure determination is essential for phase behavior prediction, process design in chemical engineering, and thermodynamic property calculations.
Tips: Enter all required parameters with appropriate units. Ensure temperature is in Kelvin and molar volume in cubic meters per mole. All values must be positive.
Q1: What is the Peng-Robinson equation?
A: A cubic equation of state that describes the relationship between pressure, volume, and temperature for real gases.
Q2: How do I determine Peng-Robinson parameters a and b?
A: These are substance-specific parameters typically calculated from critical properties and acentric factor.
Q3: What is the α-function?
A: A temperature-dependent function that accounts for molecular interactions, often related to the acentric factor.
Q4: Why use reduced pressure?
A: Reduced pressure (actual pressure divided by critical pressure) helps generalize the equation for different substances.
Q5: What are typical units for this calculation?
A: Temperature in Kelvin, volume in m³/mol, pressure in Pascals. The calculator outputs pressure in Pascals.