Actual Pressure of Real Gas using Reduced Wohl Equation given Actual and Critical Parameters Calculator

Pressure of Gas Formula:

\[ P = P_c \times \left( \frac{15 \times \frac{T}{T_c}}{4 \times \left( \frac{V_m}{V_c} - \frac{1}{4} \right)} - \frac{6}{\frac{T}{T_c} \times \frac{V_m}{V_c} \times \left( \frac{V_m}{V_c} - \frac{1}{4} \right)} + \frac{4}{\left( \frac{T}{T_c} \right)^2 \times \left( \frac{V_m}{V_c} \right)^3} \right) \]

Critical Pressure (P_c):

Temperature (T):

Critical Temperature (T_c):

Molar Volume (V_m):

m³

Critical Molar Volume (V_c):

m³/mol

Pressure of Gas (P):

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1. What is the Wohl Equation for Real Gas Pressure?

Definition: This calculator computes the actual pressure of a real gas using the reduced Wohl equation, which accounts for deviations from ideal gas behavior by incorporating critical parameters.

Purpose: It helps chemical engineers and researchers accurately predict gas pressures under non-ideal conditions.

2. How Does the Calculator Work?

The calculator uses the Wohl equation:

Where:

\( P \) — Pressure of gas (Pa)
\( P_c \) — Critical pressure (Pa)
\( T \) — Temperature (K)
\( T_c \) — Critical temperature (K)
\( V_m \) — Molar volume (m³)
\( V_c \) — Critical molar volume (m³/mol)

Explanation: The equation combines three terms that account for different aspects of real gas behavior relative to critical parameters.

3. Importance of Real Gas Pressure Calculation

Details: Accurate pressure prediction is crucial for designing chemical processes, storage systems, and understanding phase behavior.

4. Using the Calculator

Tips: Enter all required parameters in consistent units. Critical parameters are substance-specific and can be found in chemical databases.

5. Frequently Asked Questions (FAQ)

Q1: When should I use the Wohl equation instead of ideal gas law?
A: Use it when dealing with high pressures or temperatures near the critical point where ideal gas assumptions fail.

Q2: Where can I find critical parameters for my gas?
A: Chemical handbooks or databases like NIST provide critical constants for many substances.

Q3: What are typical units for these calculations?
A: SI units are recommended (Pa for pressure, K for temperature, m³ for volume).

Q4: How accurate is this equation?
A: It provides reasonable estimates near the critical point but may need adjustment for extreme conditions.

Q5: Can I use this for mixtures?
A: No, this form is for pure substances. Mixtures require additional parameters.