Question

Give two examples of irreversible changes.

Answer 1

Hint: Change is something that happens all around us. Irreversible changes, as the name suggests, are those changes which cannot revert back.

Complete step by step solution:
- Changes in the world are of two types. Reversible changes are those changes which can happen backward or reversed is called reversible change. If the change that has occurred cannot happen backward, then it is called an irreversible change. These cannot be reversed at all.
- In irreversible change, the substance cannot return to its original form once change has occurred to it. The chemical properties also cannot be reverted.
- Now examples for irreversible changes are:

1. When we burn a piece of wood. It turns into ash and smoke and disintegrates. The properties of wood changes. Chemical change occurs while burning a wood. Ash has different properties than that of the wood and it cannot be converted back to wood. Same is the case when we burn paper.
2. Iron, when exposed to air or oxygen, can undergo changes which cannot revert back. When it reacts with oxygen, it gets converted to iron oxides. This change is called rusting and the iron oxide form is called rust. The reaction occurring is a redox reaction. We can identify that iron has rusted by formation of a layer of red, flaky substance that easily crumbles into powder. Rusting can also occur due to the reaction of iron with moisture. In the rusted powder the oxidation state of iron increases.
   Thus, the two examples are, burning of wood or paper and rusting of iron.

Note: Reversible reactions can tend to obtain an equilibrium. At equilibrium, the forward and the backward reaction is at the same pace. While reversible reaction is in one direction only, that is forward direction.