Thermodynamics MCQ - Practice Questions with Answers

THERMODYNAMICS 

Thermodynamics is the branch of science which deals with the quantitative relationships between different forms of energy. Or, It deals with the energy changes accompanying physical and chemical transformations. 

Main objectives of Thermodynamics 

Its main objectives are as follows: 

• To decide the feasibility of a given transformation. 

• To derive various energy changes and their interrelations. 

• To derive laws like—phase rule, Law of mass action, etc. 

• Presentation of experimental data in a correct

Terms Related to Thermodynamics

System 

It is the region or space to be investigated or the origin at which study of pressure, temperature etc., are to be made and which is isolated from the rest of the universe with a bounding surface. 

Surroundings 

It is a region apart from the system which might be in a position to exchange energy and mass with the system.

It is to be noted that the system and surrounding together constitute the universe.

Homogeneous and Heterogeneous Systems 

Homogeneous Systems 

It is all over uniform that is made of one phase only. For example, pure liquid or pure solid, or pure gas present alone.

Heterogeneous Systems

It is non-uniform as it consists of two or more phases. For Example, ice, and water, solid in contact with a liquid.

Type of Systems 

Systems are divided into three parts-

(i) Open System: In such a system, both matter and energy can be exchanged with the sur- rounding. 

Example, Boiling of water in a beaker, Lime kiln or ice in an open beaker, Zinc granules reacting with dilute HCI to give hydrogen gas is also an example of open system as hydrogen gas escapes and the heat of reaction is transferred to the surroundings.

(il) Closed System: In such a system, exchange of energy takes place only with the surroundings. 

Example, Heating of liquid in a sealed tube or ice in a closed beaker 

(iii) Isolated System: In such a system, there is no exchange of matter or energy with the surroundings. 

Example, Liquid in a sealed thermos flask or ice m thermos flask.