Compressibility Factor Calculator
Calculate compressibility factor (Z) to determine deviation of real gases from ideal gas behavior
Calculate Compressibility Factor
Gas pressure
Actual gas volume
Amount of substance in moles
Gas temperature
Universal gas constant (automatically updated based on unit system)
Compressibility Factor Results
Physical Interpretation
Example Calculation
Air at Standard Conditions
Given:
• Pressure: P = 1 bar = 100,000 Pa
• Volume: V = 1 m³
• Number of moles: n = 44.6 mol
• Temperature: T = 293 K (20°C)
• Gas constant: R = 8.314 J/(K·mol)
Solution
Z = PV / (nRT)
Z = (100,000 × 1) / (44.6 × 8.314 × 293)
Z = 100,000 / 108,630
Z = 0.9204
Since Z < 1, the gas is more compressible than ideal gas behavior predicts.
Typical Z Values
Z = 1
Perfect ideal gas behavior
Z < 1
Attractive forces dominate
- • Lower pressure
- • Lower temperature
- • Polar gases
Z > 1
Repulsive forces dominate
- • Higher pressure
- • Higher temperature
- • Molecular volume effects
Key Principles
Equation of State
PV = ZnRT
Volume Ratio
Z = Vactual / Videal
Van der Waals
Alternative real gas model
Critical Conditions
Maximum deviation from ideality
Understanding Compressibility Factor
What is Compressibility Factor?
The compressibility factor (Z) is a dimensionless quantity that describes how much the behavior of a real gas deviates from that of an ideal gas. It's defined as the ratio of the actual molar volume of a gas to the molar volume predicted by the ideal gas law.
Physical Significance
- •Z = 1: Perfect ideal gas behavior
- •Z < 1: Gas more compressible than ideal
- •Z > 1: Gas less compressible than ideal
Mathematical Formulation
Compressibility Factor:
Z = PV / (nRT)
Where P=pressure, V=volume, n=moles, R=gas constant, T=temperature
Volume Ratio:
Z = Vactual / Videal
Ratio of actual to ideal gas volume
Modified Ideal Gas Law:
PV = ZnRT
Real gas equation of state
Factors Affecting Compressibility
Conditions Favoring Z < 1
- • Low temperature (T < Tcritical)
- • Moderate pressure
- • Strong intermolecular attractions
- • Polar molecules
- • Near condensation point
Conditions Favoring Z > 1
- • High temperature
- • High pressure
- • Significant molecular volume
- • Repulsive interactions dominate
- • Small, non-polar molecules