Question

Give an example of a physical change that is reversible and one of a chemical change that is reversible.

Answer 1

Physical change:

• A physical change is a change in which no new substance is formed.
• A physical change is temporary and reversible.
• In physical change the chemical composition of the original substance is not altered.
• For example, drying of wet clothes, breaking of a glass tumbler, drying paints, etc.

Reversible change:

• The change that can not be reversed easily to obtain a substance in its original form is called a reversible change.
• Physical changes are reversible changes.
• For example, the melting of ice is a reversible or physical change.

Chemical change:

• A chemical change is a permanent change in which new substances are formed.
• The chemical change is permanent and cannot be reversed by a simple physical method.
• A chemical change involves an exchange of energy in the form of heat or light.
• For example, rusting of iron, burning of wood, respiration, etc.

Some chemical changes can be reversed.

For example:

$3\mathrm{Fe}+4{\mathrm{H}}_2\mathrm{O}\left(\mathrm{Steam}\right)\rightleftharpoons {\mathrm{Fe}}_3{\mathrm{O}}_4+4{\mathrm{H}}_2$