Reduced Pressure Formula:
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Definition: Reduced pressure is the ratio of the actual pressure of the fluid to its critical pressure. It is a dimensionless quantity used in thermodynamic calculations.
Purpose: This calculator determines the reduced pressure of a real gas using the Clausius equation of state, which accounts for deviations from ideal gas behavior.
The calculator uses the Clausius equation:
Where:
Explanation: The equation accounts for molecular size (b'), intermolecular forces (a), and additional volume effects (c) in real gases.
Details: Reduced properties are crucial for applying the principle of corresponding states, which allows prediction of gas behavior based on critical properties.
Tips: Enter all required parameters in appropriate units. Temperature must be in Kelvin, volumes in cubic meters, and pressure in Pascals.
Q1: What are typical values for Clausius parameters?
A: Parameters vary by gas. For example, for CO₂: a ≈ 0.3653 Pa·m⁶/K·mol², b ≈ 4.28×10⁻⁵ m³/mol, c ≈ 4.2×10⁻⁵ m³/mol.
Q2: Why use reduced pressure instead of actual pressure?
A: Reduced properties allow comparison of different gases at similar states relative to their critical points.
Q3: What's the range of validity for this equation?
A: The Clausius equation works best for moderate pressures, typically below 10 times the critical pressure.
Q4: How do I find Clausius parameters for a specific gas?
A: These are typically found in thermodynamic tables or determined experimentally.
Q5: What if I get a negative reduced pressure?
A: Check your inputs. Negative values may indicate either incorrect parameters or conditions where the Clausius model breaks down.