Real gases have a factor that relates their behavior to ideal gas conditions. What is the name of this factor?

• A. Compressibility factor
• B. Z-factor
• C. Gas deviation factor
• D. Temperature correction factor

Answer: (A)

Real gases differ from ideal gases because intermolecular forces and the finite size of molecules cause deviations from PV = RT. The quantity that captures how far a real gas is from ideal behavior is the compressibility factor, Z, defined by Z = PV/(RT). It directly tells you how the actual product PV compares to what the ideal gas law would predict. If Z equals 1, the gas behaves ideally; if Z is not equal to 1, the real-gas effects are at play. The term compressibility factor is the standard name for this measure, even though you might also hear Z-factor as a shorthand. The other options aren’t the commonly used names for this concept.