Types of systems. The exchange of energy between the system and its surroundings usually takes place in the form of heat or work or both. Based upon this, the systems have been classified into three types:
(i) Open system (ii) Closed system (iii) Isolated system.

(i) Open system: A system is said to be an open system if it exchanges the matter (mass) as well as the energy with its surroundings. All chemical reactions carried in open containers constitute the open system. For example,
(a) Combustion of carbon in an open tube.


(b) Tea placed in a cup.

(ii) Closed system: A system is said to be a closed system if the only exchange of energy is possible between system and surroundings and exchange of matter (mass) is not possible. All chemical reactions carried in closed containers constitute closed system e.g.