Redlich Kwong Parameter b given Pressure, Temperature and Molar Volume of Real Gas Calculator

Formula:

\[ b = -\frac{\frac{1}{P} + \frac{\sqrt{T} \cdot V_m^2}{a} - \frac{V_m}{R \cdot T}}{\frac{1}{R \cdot T} + \frac{\sqrt{T} \cdot V_m}{a}} \]

Pressure (P):

Temperature (T):

Molar Volume (V_m):

m³/mol

Redlich-Kwong Parameter a:

Redlich-Kwong Parameter b:

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1. What is Redlich-Kwong Parameter b?

Definition: The Redlich-Kwong parameter b is an empirical parameter characteristic to the equation obtained from the Redlich-Kwong model of real gas.

Purpose: It helps correct the ideal gas law for real gas behavior, accounting for molecular volume and intermolecular forces.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ b = -\frac{\frac{1}{P} + \frac{\sqrt{T} \cdot V_m^2}{a} - \frac{V_m}{R \cdot T}}{\frac{1}{R \cdot T} + \frac{\sqrt{T} \cdot V_m}{a}} \]

Where:

\( b \) — Redlich-Kwong parameter b
\( P \) — Pressure (Pascal)
\( T \) — Temperature (Kelvin)
\( V_m \) — Molar Volume (m³/mol)
\( a \) — Redlich-Kwong parameter a
\( R \) — Universal gas constant (8.314 J/mol·K)

3. Importance of Redlich-Kwong Parameters

Details: These parameters are crucial for accurate modeling of real gas behavior, especially at high pressures and temperatures where ideal gas laws fail.

4. Using the Calculator

Tips: Enter all required values in appropriate units. Ensure temperature is in Kelvin and pressure in Pascals for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for parameter a?
A: Parameter a varies by gas (e.g., ~0.4275 for nitrogen, ~2.3026 for water vapor) and depends on critical temperature and pressure.

Q2: What units does this calculator use?
A: Pressure in Pascals, temperature in Kelvin, molar volume in m³/mol, and the result is in consistent derived units.

Q3: When is the Redlich-Kwong equation most accurate?
A: It works best for non-polar gases at moderate pressures (below 10 atm) and temperatures above the critical temperature.

Q4: How does parameter b relate to molecular size?
A: Parameter b is proportional to the actual volume occupied by gas molecules, accounting for their finite size.

Q5: Can I use this for liquid phases?
A: No, the Redlich-Kwong equation is primarily for gas phases. Modified versions exist for liquids.