Systems, open/closed/isolated

What kind of system (open, closed, or isolated) is each of the following cells (a) dry cell (b) fuel cell (c) nicad battery ... 

The state of any system, open, closed or isolated are described by state functions internal energy (U), enthalpy (H), entropy (S) and free enthalpy (G). These state functions determine whether a process is in equilibrium or may be changed spontaneously. The criterion of equilibrium at constant temperature and pressure is given by the free enthalpy, expressed by the symbol G and is defined as... 

Define the type of system open, closed, or isolated. 

If neither matter nor energy can cross the bonndary, the system is described as isolated , if only energy (bnt not matter) can cross the bonndary, the system is closed , if both matter and energy can cross the bonndary, tlie system is open. 

Identify the following systems as open, closed, or isolated (a) coffee in a very high quality thermos bottle (b) coolant in a refrigerator coil (c) a bomb calorimeter in which benzene is burned (d) gasoline burning in an automobile engine ... 

Figure 3.1 Schematic representations of thermodynamic systems a) isolated system, b) closed system and c) open system...

Remember that G, H and S are all thermodynamic functions of state, i.e. they depend only on the initial and final states of the system, not on the ways the last is reached. As we have seen, for AG = 0 the reaction has reached equilibrium (and in isolated systems AS has reached a maximum). If AG < 0 the reaction was spontaneous, but if AG > 0 the reaction could not have taken place unless energy was provided from other coupled source. If the source is external then the system is not isolated it is closed if there is no exchange of material or open if there is such exchange. In both cases the environmental changes must be taken into account. 

Any system (chemical, biological, mechanical, etc.) that does not permit the transfer of mass with its surrounding environment. Nonetheless, in closed systems, heat or energy can pass between the system and the surroundings. See Isolated System Open System... 

An example of such a system is one in which the internal energy, U, and the volume, V, are constant. If these are the only two constraints on the system then, at thermodynamic equilibrium, the entropy, S, is at a maximum. On the other hand, if entropy and volume are constant for the isolated system then, at thermodynamic equilibrium, the internal energy is at a minimum. See also Closed System Open System... 

A term used in thermodynamics to designate a region separated from the rest of the universe by definite boundaries. The system is considered to be isolated if any change in the surroundings the portion of the universe outside of the boundaries of the system) does not cause any changes within the system. See Closed System Isolated System Open System... 

ISOEQUILIBRIUM RELATIONSHIP ISOLATED SYSTEM CLOSED SYSTEM OPEN SYSTEM... 

Yet it is necessary for a clear understanding to distinguish between the logical status of (3.7) and (3.14). Equation (3.7) is merely the master equation with left-hand side set equal to zero it owes its simple form to the restriction to one-step processes. It has no physical content and applies to open systems as well, and even to non-physical systems, such as populations. On the other hand (3.14) states a physical principle pe is regarded as known from equilibrium statistical mechanics and the equation provides a connection between the transition probabilities r ,g , which must hold if the system is closed and isolated. 

All of these classifications are naturally interrelated for a given chemical/biological engineering problem, and the best approach is to choose one main classification and then use the other problem s classifications as subdivisions. The most fundamental classification of systems is usually based upon their thermodynamical characteristics. This classification is the most general it divides systems into open, closed, and isolated systems which are defined as follows ... 

Closed system A location that can exchange heat with its surroundings, but not matter. A well-sealed landfill is an example of a closed system (compare with open and isolated systems). 

In addition to the general concept of a system, we define different types of systems. An isolated system is one that is surrounded by an envelope of such nature that no interaction whatsoever can take place between the system and the surroundings. The system is completely isolated from the surroundings. A closed system is one in which no matter is allowed to transfer across the boundary that is, no matter can enter or leave the system. In contrast to a closed system we have an open system, in which matter can be transferred across the boundary, so that the mass of a system may be varied. (Flow systems are also open systems, but are excluded in this definition because only equilibrium systems are considered in this book.)... 

In physics and chemistry we call an ensemble of substances a thermodynamic system consisting of atomic and molecular particles. The system is separated from the surroundings by a boundary interface. The system is called isolated when no transfer is allowed to occur of substances, heat, and work across the boundary interface of the system as shown in Fig. 1.1. The system is called closed when it allows both heat and work to transfer across the interface but is impermeable to substances. The system is called open if it is completely permeable to substances, heat, and work. The open system is the most general and it can be regarded as a part of a closed or isolated system. For instance, the universe is an isolated system, the earth is regarded as a closed system, and a creature such as a human being corresponds to an open system. 

A system may be open, closed or isolated. An open system is one, which can exchange energy and matter with the surroundings. 

If matter is not able to pass across the boundary, then the system is said to be closed otherwise, it is open. A closed system may still exchange energy with the surroundings unless the system is an isolated one, in which case neither matter nor energy can pass across the boundary. The tea in a closed Thermos bottle approximates a closed system over a short time interval. 

Schweitz was the first to recognize that the definition of pressure is a problem in the physics of an open system. He argued that the classical result based on the properties of a closed, isolated system - a petit ensemble - must be recast in terms of an open system, a system with permeable walls, replacing the petit ensemble with the grand ensemble. This he did for both a classical... 

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