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

Critical Pressure Formula:

\[ P_c = \frac{P_r}{\left(\frac{15T_r}{4(V'_r - \frac{1}{4})}\right) - \left(\frac{6}{T_r V'_r (V'_r - \frac{1}{4})}\right) + \left(\frac{4}{T_r^2 V'_r^3}\right)} \]

Critical Pressure (P_c):

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1. What is Critical Pressure of Real Gas?

Definition: Critical pressure is the minimum pressure required to liquefy a substance at its critical temperature.

Purpose: This calculator determines the critical pressure using the reduced Wohl equation, which is essential for understanding gas behavior under various conditions.

2. How Does the Calculator Work?

The calculator uses the reduced Wohl equation:

\[ P_c = \frac{P_r}{\left(\frac{15T_r}{4(V'_r - \frac{1}{4})}\right) - \left(\frac{6}{T_r V'_r (V'_r - \frac{1}{4})}\right) + \left(\frac{4}{T_r^2 V'_r^3}\right)} \]

Where:

\( P_c \) — Critical pressure (Pascal)
\( P_r \) — Reduced pressure of gas (Pascal)
\( T_r \) — Reduced temperature (dimensionless)
\( V'_r \) — Reduced molar volume (dimensionless)

Explanation: The equation relates the critical pressure to reduced parameters that describe the gas's state relative to its critical point.

3. Importance of Critical Pressure Calculation

Details: Knowing the critical pressure helps in designing chemical processes, storage systems, and understanding phase behavior of substances.

4. Using the Calculator

Tips: Enter the gas pressure in Pascals, reduced temperature, and reduced molar volume. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What are reduced parameters?
A: Reduced parameters are actual conditions divided by their corresponding critical values (temperature, pressure, volume).

Q2: Why use the Wohl equation?
A: The Wohl equation provides a good approximation for real gas behavior, especially near the critical point.

Q3: What units should I use?
A: Pressure should be in Pascals, while reduced temperature and volume are dimensionless ratios.

Q4: How accurate is this calculation?
A: Accuracy depends on how well the Wohl equation describes your specific gas. It's generally good for many common gases.

Q5: What if I get an unrealistic result?
A: Check your input values. Reduced temperature and volume should typically be between 0 and 10 for most practical applications.