How Physical Changes Can Be Reversed: Detailed Analysis

The physical changes that occur about the state, shape, or size of an object are reversible. Let us know how physical changes can be reversed.

Some of the substances which change physically can be brought back to their original state by physical means. There are few physical changes that can not be reversed at all. When there is a change in the state of the substance, the reversibility becomes easier.

We know that there are two types of changes that occur. One is a physical change, and the other is a chemical change. Chemical changes occur when a totally new substance is formed and is generally a permanent change. In comparison, physical changes are those in which only the physical properties alter. The total internal energy remains the same, and hence they are termed as temporary changes.

Physical changes can either reverse or become irreversible. We have already reviewed irreversible physical change examples. Now let us know how physical change can be reversed. Usually, when there is a change in the state of the matter, we can bring back the initial substance by physical means.

To further understand it let us look at the example of water and ice. On freezing, water changes into ice. Water is the liquid state, and ice is the crystalline solid. Both ice and water have the same chemical formula as H₂O. So it is obvious that there have been no changes in the internal energy and composition of water. Now to reverse ice into the water, we just have to melt the ice. Similarly, we can change water into water vapor and then back to the water by condensation process. 

Let’s take the second case of salt and water solution. On adding salt and stirring it, we obtain a solution. Some might confuse it as a chemical change. But that is not the case. The solution obtained is still a physical change because when we add the salt, no change occurs in the chemical composition of water. Moreover, this process can be reversed.

On boiling the solution, the water starts changing into water vapor. And gradually it evaporates in the atmosphere. When all the water escapes away, the residue left behind is salt. This process is one of the commercial ways to manufacture salt. So, we can get back salt by the boiling process. 

Now we get the idea of how physical changes can be reversed. But not all changes are reversible. We have already seen that physical changes can be reversed and, in some cases, stay irreversible. Now let us try to reverse an irreversible physical change.

When physical factors like rain, sunlight, and wind continuously act on the rock, they start cracking. The cracks make space for these factors to break down the rocks more deeply. Slowly the rocks get deformed and change into the soil. The rock and soil both have the same composition, and hence it is a physical change. With any of the physical and chemical, this process can not be reversed back.

So now we know that reversible physical change can be brought back to its original state by physical means.

Frequently Asked Questions (FAQs)

Can physical change be reversed?

Physical changes are those changes that occur in the state, shape, size, or any such physical parameters of the object.

In many cases, physical changes are temporary that can be brought back to their initial state. This is because when a body undergoes a physical change, there is no change in its internal energy. Hence we infer that physical change can be reversed.

Is it easy to reverse physical changes?

Physical changes can be brought back into their original state, i.e., they are reversible.

In a physical change, the changes occur in the size, shape, or state of the object. The chemical composition and the total internal energy remain the same. Hence it becomes easier to reverse back the change.

Can all physical changes be reversed?

The changes that occur in the object can either be reversed or become irreversible. 

The physical changes can be both reversible and irreversible. Folding clothes is a reversible change. At the same time, cutting trees into logs is an irreversible change. Therefore not all physical changes are reversible, and not every irreversible change is a chemical change.

What is easier to reverse, physical change or chemical change?

Changes can be of two types; physical changes and chemical change.  

The chemical changes are irreversible and can’t be brought back into their initial state. Physical change can be reversed, and some of them are irreversible too. Since chemical change cannot be reversed at all, in comparison, physical change becomes easier to reverse and bring to the original state.

How physical changes can be reversed

We know that physical changes can be reversed and therefore termed as a temporary change.

When there is a change in the state of an object or substance, the physical change that occurs can be reversed back.  When this happens using physical means, the change can be reversed, and the initial substance can be brought back.

Give an example of reversible physical change?

Physical changes can be reversed to obtain the initial object. Hence it is also known as a temporary change.

An example of reversible physical change is water changing into ice. Both ice and water have the same chemical formula as H2O. Now on melting, ice changes back into the water. Therefore it is a reversible change.

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