Types of Changes: Physical change & Chemical change

Introduction and Explanation

Every day we come across meeting this in your surroundings. These changes may involve one or more substances. Curdling of milk, dissolving of sugar, sometimes milk changes its taste, etc., are some of the examples of changes. 

There are many different changes that are seen in our day-to-day life. 

They are desirable and undesirable changes, slow and fast changes, temporary and permanent changes, reversible and irreversible changes, and physical and chemical changes. All these changes involve one or more substances.  

Examples of slow change and fast changes: Growing hair or nails is a slow change and blinking of eyes is a fast change. 

Examples of permanent and temporary changes: Once the tree has been built, it cannot get back to its plant state is a permanent change. The melting of an ice cube is a temporary change. 

Examples of reversible and irreversible changes: Cutting of paper is reversible but the burning of paper is an irreversible change.   

By this, we can know that there are several changes happening in our surroundings and in our daily life. Changes can be classified into two types: 

1. Physical change 

2. Chemical change 

Physical change:  

To understand the exact meaning of physical change, let us start learning by doing some activities which help to understand in a better way. 

Activity-1: 

1. Take a paper. 

2. Cut the paper into four equal parts. 

3. Now take one part of the paper and again cut into four equal parts. 

4. Now place all this paper on a table and attach it close.  

5. You cannot join the pieces to get the original paper, but it can attain the property of paper. 

From the above activity there is a change in the shape and size of the substance.  

The substances in which there is a change in shape, size, and colour is known as physical change. When any substance is undergoing any physical change; no new substance will be formed. 

Examples of physical change: 

1. Breaking a glass. 

2. Melting of ice. 

3. Chopping of vegetables. 

4. Boiling of water. 

5. Cutting the hair.  

Chemical change:  

The chemical change is one of the changes that we see around like digestion of food, rusting of iron, chemical reactions and etc. 

To understand the exact meaning of the chemical change. We learn by doing the activities. 

Activity-2 

1. Take a pinch of baking soda and vinegar. 

2. Take a bowl, add baking soda and vinegar in it. 

3. Now you can see the reaction between these two in the below figure. 

4. This defines the chemical change. 

The above given activity defines the chemical change. 

The substances in which they undergo changes and form two or more new substances is known as chemical change. This chemical change is also called as chemical reaction.  

Examples of chemical change: 

1. Burning of food. 

2. Cooking of food. 

3. Baking of cookies 

4. Acid-base reaction 

5. [Text Box]Rotting of fruit