Free expansion
Encyclopedia
Free expansion is an irreversible process in which a gas expands into an insulated evacuated chamber.
Real gases experience a temperature change during free expansion. For an ideal gas, the temperature doesn't change, and the conditions before and after adiabatic free expansion satisfy
where p is the pressure
, V is the volume, and i and f refer to the initial and final states.
During free expansion, no work is done by the gas. The gas goes through states of no thermodynamic equilibrium
before reaching its final state, which implies that one cannot define thermodynamic parameter
s as values of the gas as a whole. For example, the pressure changes locally from point to point, and the volume occupied by the gas (which is formed of particles) is not a well defined quantity.
Real gases experience a temperature change during free expansion. For an ideal gas, the temperature doesn't change, and the conditions before and after adiabatic free expansion satisfy
where p is the pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
, V is the volume, and i and f refer to the initial and final states.
During free expansion, no work is done by the gas. The gas goes through states of no thermodynamic equilibrium
Thermodynamic equilibrium
In thermodynamics, a thermodynamic system is said to be in thermodynamic equilibrium when it is in thermal equilibrium, mechanical equilibrium, radiative equilibrium, and chemical equilibrium. The word equilibrium means a state of balance...
before reaching its final state, which implies that one cannot define thermodynamic parameter
State function
In thermodynamics, a state function, function of state, state quantity, or state variable is a property of a system that depends only on the current state of the system, not on the way in which the system acquired that state . A state function describes the equilibrium state of a system...
s as values of the gas as a whole. For example, the pressure changes locally from point to point, and the volume occupied by the gas (which is formed of particles) is not a well defined quantity.