Question

Why are physical changes generally reversible?

Answer 1

Hint: We know that a reaction is a process in which a physical or chemical change takes place which means that there are two types of changes such as physical change and chemical change. Physical change is a reversible change which means that the physical change is temporary in nature. So, we will see the reasons for the reversibility of physical change.

Complete answer:
We will see the properties that associate a physical change:
- It is a reversible process which means that this change is temporary in nature.
- In physical change, no new substance is formed.
- During this change there is no change observed in the molecular composition.
- In this process a small amount of energy or no energy is either absorbed or released.
Now, we will take the example of melting ice. In the melting of ice, there is a change in the physical state of water from solid to liquid but there is no change in the chemical or molecular composition of the water.
 $ {H_2}O(s) \rightleftharpoons {H_2}O(l) $
So, the processes in which only physical parameters change like temperature, colour and physical state are known as physical changes. Hence, the physical changes are generally reversible in nature.

Note:
There is one more type of change which can take place during a reaction which is known as chemical change. The properties of chemical change are such that it is an irreversible process, there is no change in the molecular composition of the substance undergoing chemical change. In a chemical change new substances are formed.