Critical Pressure Formula:
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Definition: Critical pressure is the minimum pressure required to liquify a substance at its critical temperature.
Purpose: This calculator determines the critical pressure using the Reduced Redlich Kwong Equation, which is important in thermodynamics and chemical engineering.
The calculator uses the Reduced Redlich Kwong Equation:
Where:
Explanation: The equation accounts for real gas behavior by incorporating reduced properties and temperature corrections.
Details: Knowing the critical pressure is essential for designing chemical processes, storage systems, and understanding phase behavior of substances.
Tips: Enter the pressure in Pascals, reduced temperature (dimensionless), reduced molar volume (must be > 0.26), and gas temperature in Kelvin.
Q1: What is reduced temperature?
A: Reduced temperature is the ratio of the actual temperature to the critical temperature of the substance (T/Tc).
Q2: What is reduced molar volume?
A: Reduced molar volume is the actual molar volume divided by the critical molar volume (Vm/Vc).
Q3: Why must reduced molar volume be greater than 0.26?
A: The equation becomes undefined at Vm,r ≤ 0.26 due to the denominator term (Vm,r - 0.26).
Q4: What are typical values for reduced temperature?
A: Values typically range from 0.5 to 2.0, with 1.0 representing the critical point.
Q5: How accurate is the Reduced Redlich Kwong Equation?
A: It provides reasonable estimates for many real gases, especially non-polar ones, but may need modification for polar substances.