Monday, 18 July 2016

PROPERTIES OF A SYSTEM


Properties of a system
Properties are the observable characteristics of a thermodynamic system.
Every system has certain characteristics by which it’s physical condition may be described. Such characteristics are called properties of the system. All properties are state or point function.
            eg÷ pressure, temperature, volume etc.
Properties may be divided into two types,
            (a) intensive properties and
            (b) extensive properties
(a)    Intensive properties
            Intensive properties are independent of the mass in the system.
            eg÷ pressure, temperature, density, specific heats etc.
(b) Extensive properties                                    
            extensive properties are depend on the mass in the system.
            eg÷ enthalpy, entropy, mass, volume etc.

State of the system
When all the properties of a system have definite values, the system is said to exist at a definite state. Properties are the coordinates to describe the state of a system. Any operation in which one or more of the properties of a system changes is called change of state. The state passes through during the change of state is called path of change of state.When the path is completely specified and defined is called a process.
eg÷ isobaric process, isochoric process, isothermal process, isentropic process etc.







Saturday, 16 July 2016

THERMODYNAMIC SYSTEMS

Thermodynamic system

A thermodynamic system is defined as a finite quantity of matter or a prescribed state in space upon in which our attention is concentrated.
The system is surrounded by an envelope called system boundary, which may be a real physical surface or it may be an imaginary surface enclosed in some matter. The boundary may be finite or it may change in shape as well as volume. Everything with in the boundary is called system, while the region external to the boundary is called surroundings.


Different types of systems

1.Closed system

If the mass within the system is remains constant is called closed system. In closed system there is no mass transfer between the system and surrounding, there is only energy transfer across the system boundary.



2. Open system


     A system in which both energy and mass transfer takes place between system and surrounding, is called as an open system.


3. Isolated system
     A system in which there is neither mass nor energy transfer across the boundary is called as an isolated system.