The compressibility factor Z equals PV over nRT. For an ideal gas its value is
- A. zero
- B. exactly 1 at all pressures
- C. always greater than 1
- D. always less than 1
Explanation
By definition an ideal gas satisfies PV equal to nRT exactly, so Z is one under every condition. For a real gas Z falls below one where attractive forces dominate and rises above one at high pressure where molecular volume dominates. Plotting Z against pressure is the standard way of displaying how far a gas departs from ideality.