Physical and Chemical Change

Question 1  What is a physical change. Give example?

Question 2 What is a chemical change. Give example ?

Question 3 Give the main differences between physical and chemical change?

Physical and Chemical Changes

Physical Changes

The changes in which no new substance are formed are called physical changes.

In a physical change, the substances involved do not change their identity. They can be easily returned to their original form by some physical changes.

For Example : Freezing of water, Boiling of water, Condensation of steam, Making a solution, Glowing of electric bulb, stretching of rubber band, cutting or tearing a piece of paper etc.

Chemical Changes

The changes in which new substance are formed, are called chemical changes.

In a chemical change, the substances involved change their identity i.e. they get converted into entirely new substance.

For Example : Burning of magnesium ribbon, Rusting of iron, Formation of curd from milk, Cooking of food etc.

Physical change	Chemical Change
(1) No new substance is formed in the physical change.	A new substance is formed in a chemical change.
(2) Physical change is temporary change.	A chemical change is a permanent change.
(3) Physical change is reversible.	Chemical change is irreversible.
(4) Very little heat or light energy is usually absorbed or given out in a physical change	A lot of heat or light energy is absorbed or given out in a chemical change.
(5) The mass of a substance does not alter in a physical change	The mass of a substance does alter in a chemical change.