The scientific reason behind both the physical and the chemical change is important to understand the characteristics of both of these changes. The reversible and irreversible nature of any components is associated with both of these changes. In a physical change, an object’s basic components change in shape, size, and colour. The chemical changes are very much different as it leads to an irreversible change that cannot be avoided while any chemical experiments are undertaken.
During a chemical change, the atoms and molecules are broken into pieces and form a new component. An individual substance turns into another substance which also leads to the differentiation of its properties (Ayyıldız, Tarhan & Gil, 2022). A physical change is easier than a chemical change. The composition of carbon dioxide is an important example of chemical change. After undergoing a chemical change, all the chemical properties are changed and this is the main reason behind the creation of a new object. Forming and changing of molecules are not seen at the time of chemical change though it happens and its results can be observed.
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Figure 1: Chemical change
Chemical changes are found in different forms. Displacement reaction, combination reaction, precipitation reaction, decomposition reaction, and double displacement reaction are important types of chemical changes (Joseph et al. 2018). During a chemical transformation and changes, any of these chemical changes take place.
Flammability, combustion, radioactive decay, toxicity, chemical stability, and pH value of an object can be regarded as chemical properties, important for a chemical change.
A physical change is such a change in which bonds within an object are untouched and unchanged as well. No bonds are formed during a physical change. This factor states that the componential attributes of an object remain the same up to the very end of a reaction. As a result, the individual properties of an object remain the same (Ge et al. 2020). During a physical change, the movement of molecules is involved. Some of the most important and recognized physical changes are physical deformation such as stretching, cutting, denting, separation of mixture, and making of a solution.
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Figure 2: Physical change of Ice into water
At a time when an ice cube melts and turns into water, a physical change takes place. At that time, the ice cube becomes able to flow without changing its composition.
Condensation and clouding: In this type of physical change, a substance is found to condense to a liquid state from a gaseous state.
Boiling liquids: In changing a liquid into a gas, boiling is done. At a certain temperature, the liquid reaches a certain level of temperature when the pressure is equal to the pressure of a gas (Cooper et al. 2019).
Freezing: This physical change is just the withdrawal of heat.
Lyophilization: In reducing the surrounding pressure, a frozen object is warmed in a vacuum. In preserving any perishable materials this process is used.
Smoke formation: As a result of vapor, smoke is generated. A mixture of combusted materials causes the formation of smoke.
The boiling point, colour, shape, and size of an object are regarded as significant physical properties.
| Physical change | Chemical change |
|---|---|
This is a reversible procedure. | This is a non-reversible procedure. |
The changes are temporary in nature. | All the changes are permanent. |
Only physical changes occur, and no new substance is formed. | A fully new substance is formed. |
No kind of energy is generated in a physical change (Steiner, 2020). | Energy, such as sound and heat is produced during a chemical change. |
In the case of no such remodelling of molecules, the composition of a substance remains the same in a physical change. | The entire composition of the molecules is changed in a chemical change. |
Physical changes are applicable only to the outer shape and colour of an object. | All chemical compositions and properties of an object are affected and changed during a chemical reaction (Ciampi et al. 2018). |
A very little amount of energy is absorbed during a physical change. | The evolution of energy, absorption, and evaporation of heat is associated with a chemical reaction that changes the overall components of an object. |
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Table 1: Difference between chemical and physical changes
Various kinds of changes are often recognized that are associated with changes in physical and chemical attributes. The primary and most basic difference between these two types of changes is that the physical change is reversible and the other one is not reversible. In reversing the chemical change, the acquired object is to go through another different chemical reaction. In the presence of sufficient energy, the physical change can be easily reversed.
Q1. What is the key difference between a chemical and a physical change?
During the time of a physical change, the form and appearance of the matter, change, and the matter type stay the same. In a chemical change, the matter types changes. As a result of a chemical change, a fully new substance can be produced that possesses all new properties.
Q2. What are the two most basic and widely observed signs of chemical and physical change?
The development of precipitate and the creation of gas are the two most significant and prominent signs of a chemical change. Changes in colour and shape are signs of physical changes.
Q3. Which three forces are responsible for leading a physical change?
Pressure, temperature, and motion are the three most basic and important forces, used in physical change. As an example, the reaction of oxygen with sugar creates a significant chemical bond which is a physical change.
Q4. What is the relation of creating a new substance with chemical and physical change?
A new substance is formed only in a chemical change. In a physical change, no such new substance is generated and formed.
Ayyıldız, Y., Tarhan, L., & Gil, A. (2022). Comparing the effectiveness of the learning material and the learning method in students’ achievement in chemistry lesson on chemical changes. Research in Science & Technological Education, 1-22. Retrieved from: https://www.tandfonline.com
Ciampi, S., Darwish, N., Aitken, H. M., Díez-Pérez, I., & Coote, M. L. (2018). Harnessing electrostatic catalysis in single molecule, electrochemical and chemical systems: a rapidly growing experimental tool box. Chemical Society Reviews, 47(14), 5146-5164. Retrieved from: https://pubs.rsc.org
Cooper, M. M., Stowe, R. L., Crandell, O. M., & Klymkowsky, M. W. (2019). Organic chemistry, life, the universe and everything (OCLUE): A transformed organic chemistry curriculum. Journal of Chemical Education, 96(9), 1858-1872. Retrieved from: https://pubs.acs.org/doi/pdf/10.1021/acs.jchemed.9b00401
Ge, S., Nemiroski, A., Mirica, K. A., Mace, C. R., Hennek, J. W., Kumar, A. A., & Whitesides, G. M. (2020). Magnetic levitation in chemistry, materials science, and biochemistry. Angewandte Chemie International Edition, 59(41), 17810-17855. Retrieved from: https://onlinelibrary.wiley.com
Joseph, S., Kammann, C. I., Shepherd, J. G., Conte, P., Schmidt, H. P., Hagemann, N., ... & Graber, E. R. (2018). Microstructural and associated chemical changes during the composting of a high temperature biochar: mechanisms for nitrate, phosphate and other nutrient retention and release. Science of the Total Environment, 618, 1210-1223. Retrieved from: https://ro.uow.edu.au
Steiner, A. L. (2020). Role of the terrestrial biosphere in atmospheric chemistry and climate. Accounts of Chemical Research, 53(7), 1260-1268. Retrieved from:https://par.nsf.gov/servlets/purl/10184713
Ncert (2022). About Physical and Chemical Changes. Retrieved from: https://ncert.nic.in [Retrieved on: 27th June 2022]
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