Actual Pressure using Redlich Kwong Equation given 'a' and 'b' Calculator

Pressure Formula:

\[ p = \frac{(2^{1/3}-1)^{7/3} \cdot R^{1/3} \cdot a^{2/3}}{3^{1/3} \cdot b^{5/3}} \cdot P_r \]

Actual Pressure (Pa):

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1. What is Actual Pressure using Redlich Kwong Equation?

Definition: This calculator computes the actual pressure of a real gas using the Redlich-Kwong equation of state, given parameters 'a' and 'b' and the reduced pressure.

Purpose: It helps in thermodynamic calculations for real gases where ideal gas law is insufficient.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ p = \frac{(2^{1/3}-1)^{7/3} \cdot R^{1/3} \cdot a^{2/3}}{3^{1/3} \cdot b^{5/3}} \cdot P_r \]

Where:

\( p \) — Actual pressure (Pascal)
\( R \) — Universal gas constant (8.314 J/mol·K)
\( a \) — Redlich-Kwong parameter a
\( b \) — Redlich-Kwong parameter b
\( P_r \) — Reduced pressure (dimensionless)

Explanation: The formula combines the Redlich-Kwong parameters with the reduced pressure to calculate actual pressure.

3. Importance of This Calculation

Details: Accurate pressure calculation is crucial for designing chemical processes, predicting phase behavior, and ensuring safety in high-pressure systems.

4. Using the Calculator

Tips: Enter the Redlich-Kwong parameters 'a' and 'b' (default values provided), and the reduced pressure. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for parameters 'a' and 'b'?
A: These vary by substance. For example, water has a ≈ 142.59 and b ≈ 0.0211 in appropriate units.

Q2: How do I obtain reduced pressure?
A: Reduced pressure is the actual pressure divided by the critical pressure of the substance.

Q3: Why use Redlich-Kwong instead of ideal gas law?
A: It accounts for molecular size and intermolecular forces, giving better accuracy for real gases.

Q4: What units should I use?
A: Ensure consistent units - the calculator uses SI units (Pa for pressure).

Q5: Can this be used for all gases?
A: It works best for non-polar or slightly polar gases at moderate pressures.