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

Wohl Parameter (b) Formula:

\[ b = V'_r \times V'_c - \frac{[R] \times (T_r \times T'_c)}{(P_r \times P_c) + \frac{a}{(T_r \times T'_c) \times (V'_r \times V'_c)^2} - \frac{c}{(T_r \times T'_c)^2 \times (V'_r \times V'_c)^3}} \]

Reduced Molar Volume (V'r):

Critical Molar Volume (V'c) [m³/mol]:

Reduced Temperature (Tr):

Critical Temperature (T'c) [K]:

Reduced Pressure (Pr):

Critical Pressure (P,c) [Pa]:

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 helps in describing the behavior of real gases by accounting for molecular size effects in the Wohl equation of state.

2. How Does the Calculator Work?

The calculator uses the Wohl equation:

Where:

\( b \) — Wohl parameter b
\( V'_r \) — Reduced molar volume
\( V'_c \) — Critical molar volume (m³/mol)
\( T_r \) — Reduced temperature
\( T'_c \) — Critical temperature (K)
\( P_r \) — Reduced pressure
\( P_c \) — 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 size of gas molecules in the Wohl equation of state, providing more accurate predictions for real gas behavior compared to ideal gas law.

4. Using the Calculator

Tips: Enter all required parameters. Default values are provided for reference. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for Wohl parameters?
A: Parameters vary by substance. For example, for CO₂: a ≈ 3.59, b ≈ 0.0427, c ≈ 2.30 × 10⁵ (in appropriate units).

Q2: How do I obtain reduced parameters?
A: Reduced parameters are actual values divided by their critical values (e.g., Tr = T/Tc).

Q3: What's the physical significance of parameter b?
A: It represents the volume excluded by a mole of particles, similar to the van der Waals co-volume.

Q4: When is the Wohl equation most accurate?
A: For moderately high pressures and temperatures, where real gas behavior deviates significantly from ideal.

Q5: How does this compare to other equations of state?
A: Wohl's equation is a three-parameter equation that can be more accurate than van der Waals but less complex than Redlich-Kwong or Peng-Robinson.