Physical Change Chemical Change - Definition, Examples, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:38 PM IST

Changes in energy are often accompanied by certain chemical changes or changes in the body. Many changes occur in the natural environment such as evaporation, congestion, rainfall, etc. Transformation is involved in all of these changes. During a reaction, the old bonds in the reactants are broken and new bonds are made in the products.

This Story also Contains

What is Chemical Change?
What are physical Changes?
What are the physical and chemical changes?
Physical Change
Chemical Modification

What is Chemical Change?

A change in the structure of cells is completely reversed and a new product is called a chemical change.

Chemical changes create a new product.

Changes in chemical reactions are irreversible and permanent.

It reveals that chemical changes cannot be reversed by modifying or modifying experimental mutations.

The quantity of matter is changed during chemical reactions. Either weight is added or removed.

During chemical reactions, energy changes occur. There is a strong difference in the breakdown of old bonds in reactants and the formation of new bonds in products.

A reaction is called a frustrating reaction when energy is released and as a response to the end of energy when energy is absorbed.

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Examples of Chemical Changes

Burning wood or paper

Camphor burns

Milk screening

Burning of a candle

Digestion

There are differences in strength during the breakdown and execution of bonds. Power is given to the environment when the required force to break the bonds is higher than the required power to make the bonds. These changes or reactions are called oddities. However, the force applied to an environment where the force required to break the bond is lower than the required force to perform the bond. Such a reaction is called an end-of-life reaction.

What are physical Changes?

During metabolic changes, the order of the molecules changes and leads to a change in mood. No new products are produced, and the molecular structure remains intact. For example, the formation of ice cells and water is not altered. No energy changes occur there due to physical changes. The energy required to bring about physical change is equal to the amount of energy needed to bring about change. There is no change in power. Changes are refundable and temporary. Response is postponed once the cause of the change is removed. For example, ice water forms ice and ice melts to form water. During a physical change, a number of things remain the same. Only power is added or removed, and size is not involved in body modification.

Examples of Physical Changes

Extinction of sugar in water

Melting snow

Cold water

Boiling water

Wax melting

Physical Changes vs. Chemicals

Introduction

There are several changes we experience every day e.g. melting sugar in water, or making a flat stick with a stick. This applies to the status quo. Changes can be categorized as:

(i) Physically

(ii) Chemicals

Body structures

Body structures include the size, shape, color and shape (solid / liquid / gas) of an object.

Physical change

Any change in the physical properties of an object is called a physical change.

Physical changes are often reversed as nothing new is built. It is the same but with different body structures.

Chemical Change

A change in the structure of one or more substances is called chemical reactions.

Often chemical changes involve chemical reactions, which create new products.

Example: Rust of Iron, or burning wood.

To find out the difference between physical and chemical changes, visit here.

Metallic oxides

The formation of iron oxides are examples of chemical reactions. They are formed by the reaction of oxygen in the air.

- Magnesium ribbon burning:

- 2Mg + O₂ → 2MgO

- A product made of magnesium oxide, which is in the form of ash. It doesn’t look anything like a magnesium ribbon used for heating.

Reaction of iron oxides with water

Iron oxide reactions have a liquid form that forms iron hydroxides.

An example of dissolving Magnesium oxide in water, by stirring the ash well with water.

MgO + H₂O → Mg(OH)₂

The manufactured product is naturally basic and turns into a red litmus → paper blue.

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Reaction between baking soda and vinegar

When a small amount of baking soda is added to the vinegar, we hear a crackling sound and notice the formation of foam.

- Vinegar (Acetic Acid) + Baking Soda (Sodium bicarbonate) → CO₂ (Carbon dioxide) + Other products

The carbon dioxide produced during the reaction of vinegar and baking soda, when passed through kalimu water provides calcium carbonate, as follows:

- CO₂ + Ca (OH)₂ (lime water) → Calcium Carbonate (CaCO₃) + H₂O

- Calcium carbonate reacts with lime water.

A look that shows a chemical change

Heat or light enters or is released during a chemical reaction.

Sound production

Gas or rain production

Fragrance production

Color change is possible

Rust

When iron elements are exposed to oxygen and moisture in the atmosphere, a red layer, called rust, forms.

The formation of rust can be indicated by the following reactions:

4Fe + 3O₂ → 2Fe₂O₃. The chemical formula for rust is Fe₂O₃.nH₂O. The more moisture in the air, the faster the formation of rust.

Galvanization

The process of applying zinc to the Iron surface to prevent corrosion is called galvanisation.

Example: Steel water pipes are installed with tin. Ships are made of cast iron. Due to the presence of salt in seawater, the corrosion process is faster. Ships therefore need to change their steel body every year.

Crystallization

The process of separating salt from their solution is called crystallization. It is a purification method that purifies seawater or separates crystals from impure samples. Physical change.

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What are the physical and chemical changes?

Everything around us has some changes. Changes can be physical or chemical. The word ‘matter’ means anything that is weighty and stays in space. It is made up of tiny particles and has many physical and chemical properties. Physical features of the body include its appearance and physical properties. Somebody's properties are color, smell, taste, melting, firmness, liquid, melting and boiling points, etc. Chemical material is the material shown during a chemical reaction. These include pH, reactivity, inflammability, etc.

Physical Change

When the subject changes its physical properties, we can say that it has undergone a physical change. Physical change is a type of change in which the physical structures of a story change. Conversion, color change, smell, melting, etc. These are all the examples of physical change. During a physical change, no structure or chemical formula is altered. During this transition, the molecules reorganize themselves without affecting the internal structure. Physical changes do not affect chemical properties.

Chemical Modification

Chemical modification is a form of change in which the chemical properties of a story change. It is often called a chemical reaction. Different substances have different chemical properties. According to this structure, objects show differences in their re-operation. This chemical reaction afterwards results in a new product. During chemical reactions, the bonds between molecules break down and the transformation process takes place. In other words, chemical reactions lead to fragmentation and bond formation.

Examples of Chemical Changes

Heat, rust, fermentation, etc. are some few examples of chemical reactions.

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NCERT Chemistry Notes:

Frequently Asked Questions (FAQs)

1. 1.What is a physical change?

Physical changes in the story sample occur when some of the properties of the object change but the nature of the story does not change. Physical changes are also divided into two categories: regenerative and non-reversible. Melting is a reversible process of the body because the melted ice cube can be regenerated.

2. 2.What are two examples of physical changes?

Changes in the size or shape of objects are examples of physical changes. Physical changes include changes from one condition to another, such as solidity to fluid or fluid to electricity. Cutting, bending, melting, freezing, boiling, melting are some of the processes that cause changes in the body.

3. 3.Why and how is a chemical change different from a physical change?

The look or feel of a story changes during a physical change, but the type of story in that does not. Chemical modification, on the other hand, leads to the creation of at least one new substance with new features.

4. 4.Is color change chemical change or physical change?

The changing of color of a substance is not necessarily an indicator of a chemical change. For example, changing the color of a metal does not change its chemical properties, hence color change is not necessarily chemical change.

5. 5.Is frying an egg a chemical change?

When you cook an egg, the liquid part of the egg turns into a liquid into a solid, which causes a chemical change. The liquid part of the egg changes color from clear to white as it cooks.

6. Why is rust formation on iron considered a chemical change?

Rust formation on iron is a chemical change because it involves the creation of a new substance (iron oxide) with different properties than the original iron. The iron reacts with oxygen and water in the air, forming a reddish-brown compound that has a different chemical composition and properties from the original iron metal.

7. How do catalysts influence chemical changes without undergoing permanent change themselves?

Catalysts speed up chemical reactions by providing an alternative reaction pathway with lower activation energy. They participate in the reaction by forming temporary bonds with reactants, facilitating the formation of products. However, catalysts are regenerated at the end of the reaction, allowing them to continue catalyzing without being consumed.

8. Can you explain why some chemical changes, like rusting, occur slowly while others, like explosions, happen rapidly?

The speed of chemical changes depends on factors such as the nature of the reactants, their concentration, temperature, and the presence of catalysts. Rusting occurs slowly because it requires the gradual interaction of iron with oxygen and water. Explosions happen rapidly due to the quick release of energy and gases, often catalyzed by heat or pressure, causing a chain reaction.

9. Why is dissolving sugar in water considered a physical change, while dissolving an antacid tablet is a chemical change?

Dissolving sugar in water is a physical change because the sugar molecules simply spread out in the water without forming new chemical bonds. The sugar can be recovered by evaporating the water. In contrast, dissolving an antacid tablet involves chemical reactions that produce new substances (like carbon dioxide gas), making it a chemical change.

10. Can you explain why cutting paper is a physical change but burning paper is a chemical change?

Cutting paper is a physical change because it only alters the size and shape of the paper without changing its chemical composition. The cellulose molecules in the paper remain intact. Burning paper, however, is a chemical change because it involves the paper reacting with oxygen in the air, breaking down the cellulose molecules and forming new substances like carbon dioxide and water vapor.

11. Can you explain why melting ice is considered a physical change?

Melting ice is a physical change because it only involves a change in the physical state of water from solid to liquid. The chemical composition of water (H2O) remains the same throughout the process. No new substances are formed, and the change can be easily reversed by freezing the water back into ice.

12. Why is the formation of fog considered a physical change?

Fog formation is a physical change because it involves the condensation of water vapor in the air into tiny water droplets. This process doesn't create any new substances

13. How do physical and chemical changes differ in their effect on intermolecular forces?

Physical changes primarily affect intermolecular forces (forces between molecules) without altering the molecules themselves. For example, melting ice weakens hydrogen bonds between water molecules. Chemical changes, however, can alter both intermolecular and intramolecular forces by breaking and forming chemical bonds within molecules, creating new substances with different intermolecular interactions.

14. How does the law of conservation of mass apply to physical and chemical changes?

The law of conservation of mass states that matter cannot be created or destroyed in a closed system. This applies to both physical and chemical changes. In physical changes, the total mass remains constant as no atoms are gained or lost. In chemical changes, while new substances are formed, the total number of atoms (and thus the total mass) remains the same before and after the reaction.

15. How do physical and chemical changes affect the electrical conductivity of substances?

Physical changes generally don't significantly alter electrical conductivity unless they change the arrangement of particles (e.g., melting a solid into a liquid). Chemical changes can dramatically affect conductivity by creating new substances with different electronic structures. For example, the chemical reaction between zinc and hydrochloric acid produces zinc chloride, which conducts electricity when dissolved in water.

16. Why is the formation of a crystal from a supersaturated solution considered a physical change?

Crystal formation from a supersaturated solution is a physical change because it involves the rearrangement of dissolved particles into a solid structure without changing their chemical composition. The molecules or ions in the solution simply organize themselves into a regular, repeating pattern, forming a crystal. No new substances are created in this process.

17. Can you explain why the formation of an emulsion (like mayonnaise) is considered a physical change?

The formation of an emulsion, such as mayonnaise, is a physical change because it involves the dispersion of one liquid (oil) in another (water or vinegar) without changing their chemical compositions. The egg yolk acts as an emulsifier, stabilizing the mixture, but no new chemical bonds are formed. The process is reversible, and the components can be separated through physical means.

18. How do physical and chemical changes affect the color of substances?

Physical changes can affect color by altering the way light interacts with a substance (e.g., crushing a colored crystal into a powder). Chemical changes can cause more dramatic color changes by altering the electronic structure of molecules, affecting how they absorb and reflect light. For example, the rusting of iron creates a new compound (iron oxide) with a distinctly different color from the original metal.

19. How do physical and chemical changes affect the magnetic properties of substances?

Physical changes generally don't significantly alter magnetic properties unless they affect the arrangement of magnetic domains (e.g., heating a magnet past its Curie point). Chemical changes can dramatically affect magnetic properties by altering the electronic structure of atoms or molecules. For example, the reduction of iron oxide to iron metal in a blast furnace changes the material from weakly magnetic to strongly ferromagnetic.

20. How do physical and chemical changes affect the solubility of substances?

Physical changes generally don't significantly alter solubility unless they affect factors like temperature or pressure. Chemical changes can dramatically affect solubility by creating new substances with different molecular structures and intermolecular forces. For example, when carbon dioxide reacts with water to form carbonic acid, the resulting solution has different solubility properties than pure water.

21. What is the fundamental difference between a physical change and a chemical change?

A physical change alters the form or appearance of a substance without changing its chemical composition. In contrast, a chemical change involves the formation of new substances with different chemical properties. Physical changes are usually reversible, while chemical changes are typically irreversible under normal conditions.

22. How can you distinguish between a physical and chemical change in everyday life?

To distinguish between physical and chemical changes, look for signs of new substance formation. Chemical changes often involve color changes, gas production, precipitation, or temperature changes without an external heat source. Physical changes typically involve alterations in shape, size, or state without creating new substances.

23. Can a change be both physical and chemical simultaneously?

While most changes are primarily either physical or chemical, some processes can involve both types of changes occurring simultaneously or in quick succession. For example, when you cook an egg, the protein molecules denature (chemical change) while the egg's physical appearance also changes (physical change).

24. What role does energy play in physical and chemical changes?

Energy is involved in both physical and chemical changes, but in different ways. Physical changes often require energy to alter the arrangement of particles without breaking chemical bonds. Chemical changes involve breaking and forming chemical bonds, which can either release energy (exothermic) or absorb energy (endothermic) from the surroundings.

25. How does the concept of reversibility apply to physical and chemical changes?

Reversibility is a key distinction between physical and chemical changes. Physical changes are generally easily reversible through simple means, like changing temperature or applying pressure. Chemical changes are typically more difficult to reverse and often require significant energy input or complex processes to return the substances to their original state.

26. Why is photosynthesis considered a complex series of chemical changes?

Photosynthesis is a complex series of chemical changes because it involves multiple steps where new substances are formed. Light energy is used to convert carbon dioxide and water into glucose and oxygen. This process involves breaking and forming chemical bonds, creating new molecules with different properties from the original reactants.

27. Can you explain why the digestion of food is considered a chemical change?

Digestion is a chemical change because it involves breaking down complex food molecules into simpler substances through chemical reactions. Enzymes in our digestive system catalyze these reactions, breaking chemical bonds in proteins, carbohydrates, and fats to produce smaller molecules that our bodies can absorb and use for energy or building new tissues.

28. How do physical and chemical changes affect the molecular structure of substances?

Physical changes do not alter the molecular structure of substances; they only affect the arrangement or state of the molecules. Chemical changes, however, involve breaking and forming chemical bonds, which results in a reorganization of atoms and the creation of new molecular structures with different properties.

29. How do physical and chemical changes affect the density of substances?

Physical changes can alter density by changing the volume of a substance without changing its mass (e.g., expanding a gas). Chemical changes can affect density more significantly by creating new substances with different molecular structures and mass distributions. For example, when wood burns, the resulting ash has a different density than the original wood.

30. How do physical and chemical changes affect the boiling and melting points of substances?

Physical changes generally don't alter boiling and melting points significantly, as they don't change the fundamental nature of the substance. Chemical changes, however, can dramatically affect these properties by creating new substances with different intermolecular forces. For example, when sodium and chlorine react to form salt, the resulting compound has a much higher melting point than either of its constituent elements.

31. Can you explain why the electrolysis of water is considered a chemical change?

Electrolysis of water is a chemical change because it uses electrical energy to break the chemical bonds in water molecules (H2O), forming hydrogen gas (H2) and oxygen gas (O2). This process creates new substances with different chemical properties from the original water. The change is not easily reversible without additional chemical reactions.

32. Why is the process of caramelization considered a chemical change?

Caramelization is a chemical change because it involves the breakdown of sugar molecules at high temperatures, forming new compounds with different flavors, colors, and aromas. This process creates various complex molecules through reactions like dehydration and polymerization, resulting in the characteristic brown color and rich flavor of caramel.

33. How do catalysts differ in their effects on physical and chemical changes?

Catalysts primarily affect chemical changes by lowering the activation energy required for a reaction to occur, thus increasing the rate of the reaction. They typically have little to no effect on physical changes. In physical changes, the rate is usually controlled by factors like temperature or pressure rather than chemical kinetics.

34. Why is the process of fermentation considered a chemical change?

Fermentation is a chemical change because it involves the conversion of sugars into other substances, typically alcohols or acids, through the action of microorganisms or enzymes. This process creates new chemical compounds with different properties from the original sugars. For example, in alcoholic fermentation, glucose is converted to ethanol and carbon dioxide.

35. Can you explain why the hardening of concrete is considered a chemical change?

The hardening of concrete is a chemical change because it involves complex chemical reactions between cement, water, and other components. When water is added to cement, it triggers a series of hydration reactions that form new chemical compounds, creating a strong, solid matrix. This process, called curing, is not easily reversible and results in a material with different properties from its original components.

36. How do physical and chemical changes affect the pH of substances?

Physical changes generally don't significantly alter pH unless they affect concentration (e.g., diluting an acid). Chemical changes can dramatically affect pH by producing or consuming hydrogen ions. For example, when an acid reacts with a base, it results in a neutralization reaction that changes the pH of the solution.

37. Why is the tarnishing of silver considered a chemical change?

The tarnishing of silver is a chemical change because it involves the reaction of silver with sulfur compounds in the air, forming silver sulfide. This new compound has different chemical and physical properties from pure silver, including a darker color. The process creates a new substance and is not easily reversible without further chemical reactions.

38. How do physical and chemical changes affect the crystal structure of solids?

Physical changes can alter the arrangement of atoms or molecules in a crystal without changing their chemical nature (e.g., phase transitions like melting). Chemical changes can dramatically affect crystal structure by creating new substances with different atomic arrangements. For example, when iron rusts, the crystal structure changes from body-centered cubic (iron) to a more complex structure (iron oxide).

39. Can you explain why the breaking of glow sticks is considered both a physical and chemical change?

Breaking a glow stick involves both physical and chemical changes. The physical change occurs when the inner container is broken, allowing two separated chemicals to mix. The chemical change happens immediately after, as these chemicals react to produce light through chemiluminescence. This reaction creates new substances and is not easily reversible, making it a chemical change.

40. How do physical and chemical changes affect the volatility of substances?

Physical changes can affect volatility by altering the state or surface area of a substance (e.g., crushing a solid increases its surface area, making it more volatile). Chemical changes can dramatically affect volatility by creating new substances with different intermolecular forces and vapor pressures. For example, when ethanol reacts with acetic acid to form ethyl acetate, the product has different volatility than either reactant.

41. Why is the process of vulcanization in rubber production considered a chemical change?

Vulcanization is a chemical change because it involves the creation of cross-links between polymer chains in rubber, typically using sulfur compounds. This process alters the chemical structure of the rubber, forming new chemical bonds that give vulcanized rubber its characteristic strength, elasticity, and resistance to degradation. The change is not easily reversible and results in a material with significantly different properties from raw rubber.

42. How do physical and chemical changes affect the refractive index of substances?

Physical changes can affect the refractive index by altering the density or arrangement of particles in a substance (e.g., applying pressure to a material). Chemical changes can cause more significant alterations in refractive index by creating new substances with different electronic structures, affecting how light interacts with the material. For example, when sugar caramelizes, the resulting compounds have a different refractive index than the original sugar.

43. Can you explain why the process of ripening fruit is considered a series of chemical changes?

Fruit ripening involves a complex series of chemical changes triggered by plant hormones like ethylene. These changes include the conversion of starches to sugars, the breakdown of chlorophyll (leading to color changes), and the softening of cell walls through enzyme activity. New flavor compounds and aromas are also produced. These processes create new substances with different properties, making ripening a chemical change.

44. How do physical and chemical changes affect the thermal conductivity of materials?

Physical changes can affect thermal conductivity by altering the arrangement or density of particles in a material (e.g., compressing a material). Chemical changes can have more dramatic effects on thermal conductivity by creating new substances with different atomic or molecular structures. For example, when carbon is transformed into diamond through high pressure and temperature, the resulting material has a much higher thermal conductivity.

45. Why is the process of photographic development considered a chemical change?

Photographic development is a chemical change because it involves the reduction of silver halide crystals in the film or paper to metallic silver, creating the visible image. This process is triggered by light exposure and enhanced by chemical developers. The reactions produce new substances (metallic silver) with different properties from the original silver halides, and the change is not easily reversible.

46. How do physical and chemical changes affect the surface tension of liquids?

Physical changes can affect surface tension by altering temperature or adding mechanical stress, but they don't change the fundamental nature of the liquid. Chemical changes can dramatically alter surface tension by creating new substances with different intermolecular forces. For example, when soap is added to water, it chemically interacts with the water molecules, significantly reducing the surface tension.

47. Can you explain why the process of nuclear fission is considered a nuclear change rather than a chemical change?

Nuclear fission is considered a nuclear change because it involves changes within the atomic nucleus, altering the very identity of the atoms involved. Unlike chemical changes, which only affect electron arrangements, nuclear fission splits atomic nuclei, creating entirely new elements. This process releases enormous amounts of energy and results in products with fundamentally different nuclear properties from the original atoms.

48. How do physical and chemical changes affect the viscosity of fluids?

Physical changes can affect viscosity by altering temperature or applying pressure, which changes how fluid molecules interact. Chemical changes can have more profound effects on viscosity by creating new substances with different molecular structures and intermolecular forces. For example, when milk sours, the chemical changes result in a thicker, more viscous substance due to protein coagulation.

49. Why is the process of cooking an egg considered a chemical change?

Cooking an egg is a chemical change because it involves the denaturation of proteins. Heat causes the protein molecules to unfold and then re-form into new structures, altering their chemical properties. This process changes the egg from a liquid to a solid state, creates new flavors and textures, an