Difference Between Chemical and Physical Reaction

Actions and reactions always go hand in hand. The environment is subject to various types of reactions depending upon their reasons. Chemical and Physical elements of the environment go through certain changes which result in reactions, chemical or physical, as termed in science. These reactions are nothing but different kinds of environmental changes that either occur naturally or artificially by introducing a separate substance into the element.

Chemical vs Physical Reaction

The main difference between Chemical and Physical Reactions is that a Chemical reaction results in the formation of a completely new substance, whereas a Physical reaction results in the reorganisation of the original molecule. A chemical reaction is irreversible, while a physical one is easily reversible. When the physical reaction is a temporary change, the chemical reaction is a permanent one.

Chemical vs Physical Reaction

A chemical reaction is a process in which the atoms of an element go through changes. As a result, rearrangement of the atoms takes place, or a completely new substance gets formed. The chemical properties and configuration of a substance change when it undergoes a chemical reaction. The ones who go through the reaction are known as reactants, and the resulted substance is known as the product.

On the other hand, a physical reaction is a process in which an element undergoes a change in terms of its physical characteristics such as state, shape, size, appearance etc. In a physical reaction, no new substance is formed. The original substance just has some rearranged physical properties, but its molecular composition remains the same.

Comparison Table Between Chemical and Physical Reaction

Parameters of Comparison Chemical Reaction Physical Reaction
MeaningWhen the chemical composition of an element changes, it is called a chemical reaction. When the physical properties of an element change but molecular composition remains the same, it is called physical reaction.
ReversibilityIt is irreversible.It is easily reversible.
New Substance A new substance gets formed.No new substance is formed.
TypeIt is a permanent change.It is a temporary change.
Enery GenerationEnergy is generated in the form of heat, sound or light.No energy generation occurs.
Energy Absorption Energy absorption occurs.Little to no energy absorption occurs.
ExamplesBurning of candle, digestion of food, rusting etc.Boiling, freezing and melting of water etc.

What is Chemical Reaction?

The process which involves a change in the chemical properties and composition of an element is called a chemical reaction. The substance or reactants go through a reaction, which changes their chemical characteristics and forms a new substance or product. The change is permanent and cannot be altered.

A chemical reaction is irreversible, i.e. it cannot be easily brought back to its original form. Once the chemical composition changes, it will require another alteration (if possible) to convert into its original form. The change occurs when bonds between certain molecules are made or broken. An element with a particular set of chemical properties is either altered or fused with another element for the formation of the new element.

After a chemical reaction, various types of changes can be seen in the resulted substance. There is a change in the temperature, i.e. either it increases or decreases. A colour shift might be observed due to alteration of the original colour or by mixing two colours. A change in its taste is also possible. After the reaction, a solid material can be observed at the end of the container called a precipitate.

Chemical reactions can be of different ranges and types. Burning of a candle, burning of natural gas in a furnace, electrolysis, precipitation, fermentation of grapes are all examples of it.

What is Physical Reaction?

The process which involves a change in the physical properties of an element is called a physical reaction. A substance goes through a reaction that changes its physical characteristics, but its chemical composition remains the same. The change is temporary and can be altered easily.

A physical reaction is easily reversible, i.e. it can be brought back to its original form once again. The changes are not very stable and can be converted by basic physical methods. An element having a certain shape, size, volume etc., experiences a change either naturally or using physical procedures.

After a physical reaction takes place, changes in the physical properties of the substance undergoing the reaction can be observed. Shape, size, colour, volume, physical appearance, state of the substance get changed. However, the molecular composition remains similar to the initial state. No new substance is formed; only alterations occur instead.

Just like chemical reactions, physical reactions can also possibly be of various ranges. Boiling of water, melting of wax, chopping wood, crumpled paper are all examples of it.

Main Differences Between Chemical and Physical Reaction

  1. The chemical reaction changes the chemical composition, while the Physical reaction changes the physical properties of an element.
  2. A chemical reaction is irreversible, but a physical reaction is easily reversible.
  3. Energy generation takes place in the case of a chemical reaction alone.
  4. A chemical reaction is a permanent alternation, but a physical reaction is just a temporary one.
  5. A new substance is formed only in a chemical reaction.
  6. Energy absorption occurs at a high rate in a chemical reaction, while in a physical reaction, there is just little or no energy absorption.


Change is the basis of living. Without changes, life loses its charm. The same goes for environmental changes as well. Chemical and Physical reactions are the changes that occur in the chemical and physical elements of the environment. They can range from very mild to extremely effective, depending upon the external factors.

Chemical reaction deals with changing the chemical composition, while Physical reaction deals with changing the physical properties. These changes either occur naturally or by using artificial methods. After the reactions, rearrangement of an element takes place, resulting in a new substance or a reorganized substance. Both chemical and physical reactions differ quite a lot.

Chemical reactions are very difficult to be reversed. In contrast, physical reactions can be reversed easily. This is because a chemical reaction is permanent, but a physical reaction is temporary. There is no energy generation visible after a physical reaction, but it is visible after a chemical reaction.


  1. https://pubs.acs.org/doi/pdf/10.1021/ar50034a005
  2. https://link.springer.com/article/10.1007/BF00281751
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