Under what conditions can the compressibility factor be assumed to be 1?

The compressibility factor (Z) is a dimensionless number that indicates how much a real gas deviates from the ideal gas behavior, where it equals 1. The correct scenario in which the compressibility factor can be reasonably assumed to be 1 is for most gases under conditions of low pressure and moderate temperatures.

At high temperatures, gases tend to behave more ideally due to increased kinetic energy, which overcomes intermolecular forces. However, it is important to note that the assumption of Z being 1 can fail at very high pressures, where interactions between molecules become significant, or at temperatures much lower than ambient, where gas behavior diverges from ideal due to condensation effects or decreased molecular motion.

Thus, for most gases, unless they are at very high pressure or extreme low temperatures, the compressibility factor can be approximated as 1, allowing for simplifying calculations in various chemical engineering applications.