Question

Why cannot a chemical change be normally reversed?

Answer 1

Chemical changes:

1. The original substance loses its identity as well as nature to form new chemical substances.
2. Some bonds are broken to form new bonds in a compound.
3. A chemical change is accompanied by a chemical reaction. A chemical reaction is the changes of atoms or molecules taking part in the reaction into new species.

For example:

Rusting of iron. When the substances made of iron are kept in the air for long period a brown layer appears on their surface.

Characteristics of chemical change:

1. There will be a change in the colour of reacting species due to chemical change.
2. There will be a change in physical state as well.
3. Sometimes the gases will evolve and precipitate may form
4. The chemical changes are of a permanent nature and they cannot be easily reversed.
5. The temperature may also change in many changes.

In a chemical change, some bonds are broken and some are formed. So, the reactants are different from the products.

After the reaction, the products formed have more stability than the reactants. So, the changes that took place are permanent.

Hence, a Chemical change cannot be normally reversed.