Laws of thermodynamics and its importance

Laws of thermodynamics and its importance


  • In today’s article, we are going to study about ‘Laws of thermodynamics and its importance’. We are going to discuss about some basics of thermodynamics, laws of thermodynamics, importance of thermodynamics, limitations of thermodynamics etc. We will also discuss some important topics like definations of thermodynamical terms and types of system. So take your notebooks in you hand and get ready to study physics in an easy and sorted way.

Laws of thermodynamics and its importance

The branch of physics in which we studied about flow of heat is called thermodynamics. Thermodynamics is a mathematical science in which we study the quantitative relationship. Hence, Thermodynamics is mainly based upon four laws which are called laws of thermodynamics.

  1. Zeroth law of thermodynamics– this law states that “If A and B are in thermal equilibrium with another system say C, then A and B are also in thermal equilibrium with each other. I.e. if two systems are in equilibrium then they will have the same quantity of hotness (temperature).
  2. First law of thermodynamicsEnergy of whole universe is constant.
  3. Second law of thermodynamics– second law of thermodynamics states that Entropy is increasing for universe.
  4. Third law of thermodynamicsEntropy of a perfectly crystalline solid is zero at zero Kelvin.

Importance of thermodynamics

Thermodynamics help us to lay down the criteria for predicting feasibility or spontaneity of a physical or chemical process under given conditions of pressure, temperature etc. It also helps us to determine the extent to which a process can proceed before attainment of equilibrium. Above laws help up to find out the feasibility of chemical and physical processes.

Limitations of thermodynamics

  • Laws of thermodynamics can not applied to individual molecules or atoms. They are applicable to matter in bulk.
  • The second limitation of thermodynamics is that it can only give the information about the feasibility of a process whether it is physical or chemical under given conditions. It does not give the rate at which a given process may proceed or time for completion for process. And Thermodynamics concerns only with initial and final state of a system. For instance we can know from thermodynamics that when oxygen and hydrogen react at ordinary temperature, water is formed but it does not tell whether the reaction is fast or slow. We can only know from other experiments that reaction is very slow in absence of a catalyst.

Definition of thermodynamical terms

System– Any specified portion of matter under thermodynamics study which can be separated from rest of the universe with boundaries is called system.

Surrounding– The rest of the universe other than system which have ability to exchange energy and matter with the system is termed as the surrounding.

Types of Systems

  1. Isolated system– A system is said to be isolated system if it doesn’t exchange neither energy nor matter with its surrounding. Hot water is a thermosflask is the example of an isolated system.
  2. Closed system– A system which can exchange energy but nor matter with its surrounding is called a closed system. Hot water in a closed container is the example of closed system.
  3. Open system– A system which can exchange matter as well as energy with its surrounding is called open system. Hot water containing in a open container is the example of open system.
  4. Homogeneous system– A system is said to be homogeneous when it have uniform composition. It has only one phase. For example, a pure solid or liquid or a solution or a mixture of gases.
  5. Heterogeneous system– A system is said to be heterogeneous system when it is not uniform throughout. This system is contains more than one phase. A system consisting of two or more immiscible liquids i.e it will not fix with each other or a solid in contact with a liquid in which it does not mix is the example of heterogeneous system.

Laws of thermodynamics and its importance

State of Systems

The state of a system is fixed by its macroscopic properties like temperature, pressure, volume and composition. These are called variables of state. These are called variables of state. When they are fixed for a system, the system is said to be in a definite state. Generally chemical composition is fixed for a system in thermodynamical study. So only three variables i.e. pressure, volume and temperature are to be fixed to define the state of a system.


In this article we have discussed basic definations of thermodynamics, its laws, need etc in detail. We have also covered some other topics like thermodynamical terms and types of system in easiest way possible. Hence now one can easily clarify himself/herself about there topic related to this article. Your suggestions are invited for more information on other topics.

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