When to use the Ideal gas law and the compressibility factor when solving a thermodynamic problem?

At very low pressure and at high temperature gases behaves like ideal gas. Ideal gas follows P V = m R T (ideal gas equation)

Where P is the pressure

V is the volume

m is the mass

R is gas constant

T is the temperature

Properties of ideal gas like internal energy, enthalpy depends only on the temperature.

But in actual practice all real gases are deviate from ideal gas conditions and for evaluating the property of real gases we multiple one factor in the ideal gas equation, this factor is known as compressibility factor (Z).

P V = Z m R T

For ideal gas Z = 1.