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A closed system is a natural physical system that does not allow transfer of matter in or out of the system, although – in the contexts of physics, chemistry, engineering, etc. – the transfer of energy (e.g. as work or heat) is allowed.
Properties of isolated, closed, and open thermodynamic systems in exchanging energy and matter. A thermodynamic system is a body of matter and/or radiation separate from its surroundings that can be studied using the laws of thermodynamics. Thermodynamic systems can be passive and active according to internal processes.
The concept of an isolated system can serve as a useful model approximating many real-world situations. It is an acceptable idealization used in constructing mathematical models of certain natural phenomena; e.g., the planets in the Solar System, and the proton and electron in a hydrogen atom are often treated as
One such potential is the Helmholtz free energy (A), for a closed system at constant volume and temperature (controlled by a heat bath): = Another potential, the Gibbs free energy (G), is minimized at thermodynamic equilibrium in a closed system at constant temperature and pressure, both controlled by the surroundings:
The history of statements of the law for closed systems has two main periods, before and after the work of George H. Bryan (1907), [35] of Carathéodory (1909), [27] and the approval of Carathéodory's work given by Born (1921). [26] The earlier traditional versions of the law for closed systems are nowadays often considered to be out of date.
A 1993 paper, General Systems Theory by David S. Walonick, Ph.D., states in part, "A closed system is one where interactions occur only among the system components and not with the environment. An open system is one that receives input from the environment and/or releases output to the environment.
In thermodynamics, an adiabatic wall between two thermodynamic systems does not allow heat or chemical substances to pass across it, in other words there is no heat transfer or mass transfer. In theoretical investigations, it is sometimes assumed that one of the two systems is the surroundings of the other.
In thermodynamics, the phase rule is a general principle governing multi-component, multi-phase systems in thermodynamic equilibrium.For a system without chemical reactions, it relates the number of freely varying intensive properties (F) to the number of components (C), the number of phases (P), and number of ways of performing work on the system (N): [1] [2] [3]: 123–125