Question

State whether a chemical change is reversible or irreversible.

Answer 1

A chemical change is an irreversible change i.e, the change cannot be reversed to bring the substance that has undergone change back to its original form or state.

• Example: Burning of wood
• Once the wood is burnt and Carbon-dioxide $\left({\mathrm{CO}}_2\right)$ and Water $\left({\mathrm{H}}_2\mathrm{O}\right)$ is produced along with ash, wood cannot be returned to its original state. Hence, it is an irreversible process.

Chemical change: A change in which one or more new substances are formed and there is a change in the chemical composition of the substance undergoing the change.

• It is a permanent change.
• It is an irreversible change as the substance undergoing change can not be brought back to its original state.
• A change in physical as well as chemical change is observed during a chemical change.
• Energy is either consumed when bonds are broken or released when chemical bonds are formed.
• Examples: Rusting of Iron $\left(\mathrm{Fe}\right)$, Burning of wood.