Matter can undergo many changes in properties like state of matter, shape, chemical properties like a chemical formula, etc. The change can be classified into types: physical and chemical. The difference between physical and chemical change is that the properties affected are physical or chemical in nature. Like when the ice cream melts, the change is physical as only the state of matter changes from solid to liquid but the taste and other properties remain the same. Photosynthesis is an example of a chemical reaction, where sunlight, carbon dioxide, and water is converted to sugars. Other examples of chemical change include rusting and milk becoming curd. In this article, we discuss 10 differences between physical and chemical change.
What are physical changes?
Physical change is a change in matter when the change does not produce a fundamentally different substance. For example, when the ice melts, it gets converted into liquid water, but in both states, it is water only. The chemical composition remains the same as H2O. On a fundamental level, the matter is the same but there can be physical changes after the change. There is no breaking or joining of chemical bonds. The properties that can change after a physical change are a density, shape, state of matter, etc.
What are chemical changes?
A chemical change involves a change in the chemical composition of matter. Like iron turns into rust after rusting, milk turns into curd, etc. The substance undergoes a transformation into a new substance. It involves the breaking or making of interatomic bonds.
Difference between physical and chemical changes
| Physical Change | Chemical Change |
| The composition of the material remains the same. Water in (solid) ice form is H2O and in liquid and gaseous(steam) state. | In a chemical reaction, the molecular structure of the substance is changed completely. For example, when we burn magnesium ribbon it transforms into magnesium oxide. |
| The physical change is a temporary change. Like ice, after it is melted it can be again solidified to ice. The water from the sea is evaporated and then is condensed to come down as rain. | Chemical changes are permanent. Like, iron after it gets rusted it cannot be resorted again to iron easily. |
| The physical change affects properties that are physical like shape, size, density, etc. | A chemical change can affect both physical and chemical properties like rusting affects the color texture, chemical formulae, etc. |
| During a physical change generally, the energy absorbed or released is very less compared to chemical changes. | The absorption and evolution of energy during a chemical reaction like a nuclear fission reaction are much larger than a physical change. |
| No new substances are formed in physical change. Like, in ball milling, a process to produce powder, the substance will be the same just in powder form. | In a chemical change, new substances can be formed. Like, in photosynthesis, plants use carbon dioxide, water, and sunlight to synthesize sugar molecules. |
| Physical change generally involves changes in physical properties like size, and shape and does not involve the release of light, sound, heat, etc. | A chemical change can produce energy in the form of light, heat, sound, etc. |
| Physical changes are reversible and we get the same state in most cases. We can melt ice and again solidify to ice. | Chemical changes are irreversible, and there is very little chance of reverting to the original state. Like for example, iron rust cannot be restored to iron again. |
| Physical changes can be caused by the use of mechanical forces like grinding, polishing, etc. | It is difficult to create chemical changes using mechanical forces. |
| Examples of physical change: are freezing of water into ice, ball-milling, grinding, sublimation of camphor, and boiling of water. | Examples of chemical change: Burning of coal, formation of milk into curd, rusting of iron, digestion of food, etc. |
| Applications of physical changes include the separation of compounds by distillation, making powders of substances, changing the texture or shape of materials, etc. | Application of chemical change includes chemical reaction for the synthesis of novel chemical molecules with specific properties, generation of energy like biogas plant, etc. |
Difference between physical and chemical change using examples
Grinding a material like a chili into chili powder involves a change in texture, shape, and size of the material. Though the material is still the same, chili. It does not get transformed into tomatoes due to grinding. This is called a physical change. But when food like chili is digested by our stomach it gets transformed into simpler chemical molecules in our body. Now the chemical composition is changed, it is no more chili. This is called a chemical change.
The water cycle is an example of physical change, where the water from seas or oceans is evaporated to water vapor (gaseous state). Then the gaseous water is then condensed in the clouds to form liquid water and is precipitated in form of rain. This process of condensation and evaporation is an example of physical change. You can read more about condensation in this article.
Water reacts with sodium to form sodium hydroxide. Na + H2O –> 2NaOH + H2 . This is a chemical reaction as the end products are different from the starting material.
