Redlich-Kwong Parameter a Formula:
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Definition: The Redlich-Kwong parameter a is an empirical parameter characteristic to the equation obtained from the Redlich-Kwong model of real gas.
Purpose: It helps in describing the behavior of real gases, particularly near the critical point, where ideal gas laws fail.
The calculator uses the formula:
Where:
Explanation: The formula relates the parameter a to the critical temperature and pressure of the substance.
Details: This parameter is essential for accurate modeling of real gas behavior in chemical engineering and thermodynamics applications.
Tips: Enter the critical temperature in Kelvin and critical pressure in Pascals. Both values must be > 0.
Q1: What are typical values for parameter a?
A: Values vary by substance. For water at critical point (647 K, 21800000 Pa), a ≈ 1.44×10⁶ Pa·m⁶·K¹/²/mol².
Q2: Why is the critical temperature raised to the 5/2 power?
A: This empirical relationship was found to best describe the temperature dependence of real gas behavior.
Q3: What are the units of parameter a?
A: The SI units are Pa·m⁶·K¹/²/mol², but it may be expressed in different units depending on the equation of state form.
Q4: How does this relate to the Redlich-Kwong equation of state?
A: Parameter a is used in the attraction term of the Redlich-Kwong equation: P = RT/(V-b) - a/(√T V(V+b)).
Q5: What's the difference between parameters a and b?
A: Parameter a accounts for intermolecular attractive forces, while b accounts for molecular volume.