When Does A Physical Change Occur: Detailed Analysis

The changes happening around us are either chemical or physical changes. Let’s have knowledge about when does a physical change occur. 

Physical changes occur when the substance undergoes a transition in the physical properties. Any change in the state, shape, color, or size of the object is said to be a physical change. They are generally known as temporary changes. The physical change can either be reversible or irreversible. 

A physical change arises due to changing physical properties, i.e., size, shape or state, etc. Generally, physical change is caused by applying force or energy to the object. During a physical change, the total internal energy before and after the reaction or change remains the same. This means that the bonds of the object or substance remain intact. It does not break to form a new substance. 

Let us understand a common example of physical change that is the melting of butter or vice versa. For melting butter, energy is required. Now this energy should be sufficient enough to change the state of the butter and does not break the bonds. When the butter acquires this energy, its molecules gain energy and come in rapid motion. Due to this, they only get apart and change into a liquid state. And hence physical change occurs. 

This change can be reversed, and butter can regain its original state on freezing, thus leading to phase change. Now physical change can also occur by changes in size, shape, odor, color, temperature, or pressure. Now when you break a pencil into two halves, its shape and size both get changed, and hence physical change has occurred. 

Image Credit: Andy Schmitz, Sodium chloride dissolutionCC BY 3.0

Let’s take another case of sugar dissolving into the water. Now, this is a common example of reversible physical change. Many a time, it is confused to be a chemical change. For this, let us see how a physical change occurs. On dissolving sugar into water, no new substance is formed with no chemical reaction. During the process, the thing that happens is the change in form. The identity of both the solute and solvent remains the same. Here the water that is our solvent gets its molecules further apart, and sugar molecules fill that space. Hence this process occurs. 

Now it is easy to reverse back the process and generate sugar back from the solution. The vaporization process, along with condensation and crystallization, will bring back the molecule. Hence now we know when does a physical change occur. 

Frequently Asked Questions (FAQs)

Name two types of changes that can occur. 

There are two types of changes that are known to humans; chemical change and physical change.

The change that forms a new substance by altering the chemical composition of the substance is said to be a chemical change. All the modifications that happen in the physical characters are inferred as physical change. There is no formation of new substances during the physical change. 

Explain the physical change. 

The changes happening about the physical properties of the object, substance, or compound is said to be physical change. 

It involves changes in size, shape, color, odor, temperature, or pressure. Physical changes are said to be temporary changes. They can be reversed to bring back to the primary state, and some are irreversible too. E.g.:- broken glass, tearing paper, chopping vegetables. 

When does a physical change occur? 

Physical changes can be reversed or stay irreversible depending upon the situation. 

A physical change occurs when there is any kind of alteration in the physical properties of the object. The changes can be just temporary or become irreversible. These changes do not lead to the formation of any new substance. 

Is physical change temporary or permanent change?

Physical changes can be reversed back to their initial state by physical means. 

Since physical change can be reversed, it is said to be a temporary change. The chemical change is known to be a permanent change. But remember, not all physical changes are reversible, like cutting trees into logs. 

How to know the physical change has taken place? 

Since the physical change brings changes in the physical properties of the substance, it can easily be seen. 

If you see a change in any physical characteristics of the object, know that physical change has taken place. For example, when you drop a glass, it breaks into smaller pieces. The size and shape get deformed on hitting the floor. Hence physical change has occurred.

What are the signs of physical changes? 

The change in physical properties is classified as physical change. 

The signs of physical change are shape, size, color, matter, odor, temperature, and pressure. Any change in the following properties indicates that the physical change has taken place. These changes can clearly be observed by us and in the most cases are reversible.

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