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Conversion of States of Matter

Conversion of States of Matter for Class 5 Science

Through this concept, the students will be introduced to the conversion between the three states of matter. They will understand how solids can be transformed into liquids and how liquids can be transformed into gases and vice versa.

After reading the concept, students will be able to:

  • Explain what is melting and the factors that initiate the melting of a solid substance.
  • Explain the evaporation process and know how liquids evaporate.
  • Describe condensation reaction and enlist the difference between evaporation and condensation.
  • Know what is freezing and can explain what is freezing point.
  • Know the boiling point of water is 100 degrees Celsius.
  • Explain what is melting point.


Each concept is explained to class 5 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.

Download the worksheets and check your answers with the worksheet solutions for the concept of Conversion of States of Matter provided in PDF format.


What is Conversion of States of Matter?

Matter can change from one state to another, i.e., a solid can change into a liquid or vice versa, a liquid can change into a gas and vice versa.

Example:The most common example of such a phenomenon is the conversion of water (a liquid) into ice (a solid) and water vapour (a gas) and the other way round.

water vapour

The factors regulating the conversions of states of matter are—

  • Temperature: It causes the molecules of the substance to move faster or slower.
  • Pressure:It controls how the molecules of the substance will be packed—closely packed or loosely packed.

Let us now look at the different processes involved in the change of states of matter.



The conversion of the liquid state of matter into the gaseous state is called evaporation.

Example:When water is heated, it gets converted into steam.

An increase in temperature leads to an increase in the speed of the molecules.Beyond a specific temperature, the intermolecular force among the liquid molecules weakens, and the molecules start moving freely, thereby changing into the gaseous state.
  • The temperature at which the liquid molecules attain sufficient energy to overcome the intermolecular force of attraction and become a gas is called the boiling point.



The conversion of the gaseous state of matter into the liquid form is called condensation.A decrease in temperature brings the molecules closer, leading to condensation, thereby converting the gas into a liquid.

Example:Have you ever seen water droplets on the surface of a cold glass? They are actually the water vapours that get converted into water droplets when they come in contact with the cold surface of the glass.



The conversion of a solid into a liquid due to an increase in temperature is called melting.

Example:When we keep a cube of ice or butter outside the freezer, it melts after some time.

  • Due to an increase in temperature, the intermolecular force of attraction weakens and the solid changes into a liquid.
  • The temperature at which a solid gets converted into a liquid is called the freezing point.



The conversion of a liquid into a solid due to a change in the temperature is called freezing.

Example:When we keep water in the freezer, it turns into ice.

A decrease in the temperature leads to a decrease in the speed of molecules. It fixes them at a place, so the change of state occurs.The temperature at which this conversion happens is called the melting point.


Change of state due to application of pressure is most common among gases than solids and liquids.

The reason is that the intermolecular space in solids and liquids is relatively less than gases which does not change much when pressure is applied to them.However, in gases, as the intermolecular space is huge, the application of pressure turns a gas into a liquid.

Example:Carbon dioxide gas changes into a liquid when sufficient pressure is applied to it.


 New Words:

Temperature: The degree of hotness and coldness of a body. It can be measured by a thermometer.

Pressure: The physical force exerted per unit area of an object.


Did You Know?

Have you ever wondered why the size of naphthalene balls kept in clothes keeps on decreasing every day? It happens because naphthalene balls keep on evaporating. The conversion of a solid directly into vapour is called sublimation.


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