For an ideal gas, the enthalpy is independent of pressure.

For a real gas going through an adiabatic reversible process, the process equation is given by PVγ= constant, where P is the pressure, V is the volume and y is the ratio of the specific heats of the gas at constant pressure and constant volume.

For an ideal gas undergoing a reversible polytropic process PV^1.5 = constant, the equation connecting the pressure, volume and temperature of the gas at any point along the process is P/R = mT/V, where R is the gas constant and m is the mass of the gas.

Any real gas behaves as an ideal gas at sufficiently low pressure or sufficiently high temperature.