Those change in which new substance are formed are called chemical change.
- In the chemical change the original substance lose their identity and get converted into new substance.
- The new substance thus formed can not converted back into original substance by any physical process.
- Thus chemical changes are permanent and hence are irreversible.
Example of chemical change:
- Burning of piece of paper:
- When piece of paper burn in air with lighter or match stick , entirely new substance Such as carbon dioxide, smoke ash are formed.
- Thus burning of paper is a chemical change.
- Rusting of iron:
- When iron articles are exposed to air and moisture for a few days, a brown colour substance called iron sulphide are formed.
- Since iron sulphide cannot converted by any physical process back to iron and sulphur there for formation of iron and sulphur is a chemical change.
- Burning of magnesium ribbon:
- When a magnesium ribbon is heated a strongly it burn with dazzling light to form a white powder of magnesium oxide.
- The magnesium oxide thus formed is entirely new substance.
Question Answer
1) What is chemical change?
Answer: Those change in which new substance are formed are called chemical change.
2) Write Properties of chemical change?
Answer: • In the chemical change the original substance lose their identity and get converted into new substance.
- The new substance thus formed can not converted back into original substance by any physical process.
- Thus chemical changes are permanent and hence are irreversible.
3) Give example of Chemical Change?
Answer: 1) Burning of piece of paper:
- When piece of paper burn in air with lighter or match stick , entirely new substance Such as carbon dioxide, smoke ash are formed.
- Thus burning of paper is a chemical change.
2) Rusting of iron:
- When iron articles are exposed to air and moisture for a few days, a brown colour substance called iron sulphide are formed.
Since iron sulphide cannot converted by any physical process back to iron and sulphur there for formation of iron and sulphur is a chemical change.