Wohl Parameter (b) of Real Gas using Wohl Equation given Actual and Critical Parameters Calculator

Wohl Parameter (b) Formula:

\[ b = \frac{V'_m}{V'_c} \times V'_c - \frac{R \times T_{rg}}{P_{rg} + \frac{a}{T_{rg} \times V'_m^2} - \frac{c}{T_{rg}^2 \times V'_m^3}} \]

Molar Volume of Real Gas (V'm):

m³

Critical Molar Volume (V'c):

m³/mol

Temperature of Real Gas (T_rg):

Critical Temperature (T'c):

Pressure of Gas (P_rg):

Critical Pressure (P,c):

Wohl Parameter (a):

Wohl Parameter (c):

Wohl Parameter (b):

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1. What is Wohl Parameter (b) of Real Gas?

Definition: Wohl parameter b is an empirical parameter characteristic to equation obtained from Wohl model of real gas.

Purpose: It's used in the Wohl equation of state to describe the behavior of real gases, accounting for molecular volume and intermolecular forces.

2. How Does the Calculator Work?

The calculator uses the Wohl equation:

\[ b = \frac{V'_m}{V'_c} \times V'_c - \frac{R \times T_{rg}}{P_{rg} + \frac{a}{T_{rg} \times V'_m^2} - \frac{c}{T_{rg}^2 \times V'_m^3}} \]

Where:

\( b \) — Wohl parameter b (to be calculated)
\( V'_m \) — Molar volume of real gas (m³)
\( V'_c \) — Critical molar volume (m³/mol)
\( T_{rg} \) — Temperature of real gas (K)
\( T'_c \) — Critical temperature (K)
\( P_{rg} \) — Pressure of gas (Pa)
\( P,c \) — Critical pressure (Pa)
\( a \) — Wohl parameter a
\( c \) — Wohl parameter c
\( R \) — Universal gas constant (8.314 J/mol·K)

3. Importance of Wohl Parameter (b)

Details: The Wohl parameter b accounts for the finite volume occupied by gas molecules, which becomes significant at high pressures where the ideal gas law fails.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Default values are provided for common gases, but should be adjusted for specific substances.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for Wohl parameters?
A: Parameters vary by substance. For example, for CO₂: a ≈ 365, b ≈ 0.0427, c ≈ 4.28 × 10⁶.

Q2: When is the Wohl equation most accurate?
A: It works best for moderately non-ideal gases at pressures up to about 10 times critical pressure.

Q3: How do I get critical parameters for my gas?
A: Critical properties are tabulated in chemical engineering handbooks and databases.

Q4: What's the difference between Wohl parameters and van der Waals constants?
A: Both account for molecular interactions, but Wohl's equation uses three parameters (a, b, c) for better accuracy.

Q5: Can I use this for liquid phases?
A: No, the Wohl equation is designed for gas phases only.