Physical Changes

Change in which no new substance is formed is called Physical Change.

These changes are reversible

Example

When ice melts into water , it is a physical change

It is because ice and water are chemically same (both are H 2 O)

Also we can convert ice back into water

Hence, this change is physical change.

Chemical Changes

Changes in which new substances are formed are Chemical Changes.

These changes are normally irreversible

Example

Burning is chemical change

When a paper is burnt, it turns into carbon

This change cannot be reversed to get back paper

Hence, this change is chemical change.

 

 

Difference Between Physical Change and Chemical Changes

 

Physical Changes

Chemical Changes

No new substance is formed

New Substance is formed

This change is reversible

This change is normally irreversible

Very little heat or light energy is absorbed or given out in Physical change

A lot of heat or light energy is involved in process

It is also called Physical Reaction

It is also called Chemical Reaction

Examples

Interconversion of States of matter is Physical change

Tearing of paper

Examples

Burning is a chemical reaction

Cooking of food



 

Whether following are Physical Change or Chemical Change?

 

1. Burning of Candle

 

Physical Change and Chemical change

  • When a candle is burnt, its wax melts from solid to liquid and no new substance is formed, hence its a physical change. 
  • But the burning of the vapour is a chemical change.

 

2. Cutting of Trees

 

Physical change

During cutting of trees no new substance is formed , hence its a physical change.

 

3. Rusting of Almirah (Rusting of Iron)

 

Chemical Change

Rusting is a chemical reaction in which iron reacts with oxygen to form a new substance called rust (ferric oxide) , hence its a chemical change

4. Passing of Current in Water

 

Chemical Change

Passing current in water breaks it into Hydrogen and Oxygen, hence new substances are formed . Therefore, its a chemical change

 

5. Making of Fruit Salad with Raw fruits

Physical Change 

No new substances are formed hence it is a Physical change.


6. Burning of Paper and Wood

Chemical Change

When we burn paper and wood, new substances are formed like carbon and smoke

This change cannot be reversed

 

7. Melting of Butter in pan

Physical change

It is a change of state of matter from solid to liquid

This change is temporary and can be reversed.



8. Dissolving of Salt in Water

 

Physical change 

The change can be reversed to get back salt and water

This can be done by heating solution of salt and water

Water will convert into water vapour and we can get salt at the bottom of container



9. Breaking of Glass Tumbler

 

Physical change

No new substance is formed

When a glass tumbler breaks, different pieces of broken glass are still same substance (glass)



10. Switching on of Electric Bulb

 

Physical change 

The change is temporary and can be reversed

When bulb is switched on, the filament of bulb becomes hot and gives heat and light

However when bulb is switched off, it turns back into original state

Hence this change is temporary.



11. Heating of Magnesium Wire

 

It is a chemical change because a new substance is formed.

When a magnesium wire is heated, it forms a new substance magnesium oxide which is a completely different substance from magnesium.

 

Question

Burning of Candle is Both Physical and Chemical Change. How?

When candle burns, wax in candle converts from solid into liquid

This is a physical change (as it is a change in state of matter and can be reversed)

However, wax near the flame burns and convert into carbon dioxide

This carbon can’t be again converted into wax , so this is a chemical change.

  1. Class 9
  2. Chapter 2 Class 9 - Is Matter Around Us Pure

About the Author

Davneet Singh's photo - Teacher, Computer Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.