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

Wohl Parameter (a) Formula:

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

Reduced Temperature (T_r):

Critical Temperature of Real Gas (T'_c):

Reduced Molar Volume (V'_r):

Critical Molar Volume (V'_c):

m³/mol

Wohl Parameter (b):

Wohl Parameter (c):

Reduced Pressure (P_r):

Critical Pressure (P'_c):

Wohl Parameter (a):

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1. What is Wohl Parameter (a)?

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

Purpose: It helps in describing the behavior of real gases, accounting for intermolecular forces and molecular volume.

2. How Does the Calculator Work?

The calculator uses the Wohl equation:

Where:

\( a \) — Wohl parameter a
\( [R] \) — Universal gas constant (8.314 J/mol·K)
\( T_r \) — Reduced temperature
\( T'_c \) — Critical temperature (K)
\( V'_r \) — Reduced molar volume
\( V'_c \) — Critical molar volume (m³/mol)
\( b \) — Wohl parameter b
\( c \) — Wohl parameter c
\( P_r \) — Reduced pressure
\( P'_c \) — Critical pressure (Pa)

3. Importance of Wohl Parameter Calculation

Details: Accurate calculation of Wohl parameters is essential for modeling real gas behavior in chemical engineering applications, particularly at high pressures and temperatures.

4. Using the Calculator

Tips: Enter all required parameters. Reduced properties are dimensionless ratios. Critical properties are substance-specific and can be found in reference tables.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for Wohl parameters?
A: Parameters vary by substance. For example, for CO₂: a ≈ 0.365, b ≈ 0.0427, c ≈ 0.00014 (in appropriate units).

Q2: How do I find critical properties for a substance?
A: Critical properties are tabulated in chemical engineering reference books and databases like NIST Chemistry WebBook.

Q3: What's the difference between reduced and critical properties?
A: Reduced properties are ratios of actual to critical properties (dimensionless), while critical properties are substance-specific constants.

Q4: When is the Wohl equation most accurate?
A: The Wohl equation works best for moderately non-ideal gases at conditions not too far from critical.

Q5: What are the units of Wohl parameter a?
A: The units depend on the equation form, but typically Pa·m⁶·K⁰.⁵/mol² or similar.