A very small part of universe in which experiments are done and observations are made, this small part of universe is called system.
There are three types of the system.
(1) Open System : In an open system, there is exchange of energy and matter between system and surroundings Figure (a).
The presence of reactants in an open beaker is an example of an open system.
(2) Closed System : In a closed system, there is no exchange of matter, but exchange of energy is possible between the system and the surroundings [Fig. (b)]. The presence of reactants in a closed vessel made of conducting material. e.g., copper or steel is an example of a closed system.
(3) Isolated System : In an isolated system, there is no exchange of energy or matter between the system and the surroundings [Fig. (c)].
The presence of reactants in a thermos flask or any other closed insulated vessel is an example of an isolated system.
