Key Differences Between Physical and Chemical Changes (Table & Examples)
Understanding the difference between physical and chemical change is crucial for mastering fundamental Chemistry, especially for JEE Main. Both are ways matter transforms, but the type of alteration, reversibility, and identification methods vary sharply. In any JEE question, physical changes are those that affect the state or appearance of substances without altering their internal composition, while chemical changes lead to formation of new substances with distinct properties. Recognising whether ice melting or iron rusting is physical or chemical comes up again and again in MCQs and theory, making fast recall and clarity essential for exam success.
What is a Physical Change? Definition & Examples
Physical changes refer to alterations in matter that do not create any new substance. Only physical properties—such as shape, state (solid, liquid, gas), colour, or size—undergo change. The composition at the molecular level remains unchanged. Most are reversible and do not involve breaking or forming new chemical bonds.
- Melting of ice to water (H2O remains H2O)
- Boiling water into steam
- Dissolving sugar in water
- Breaking glass
- Magnetising an iron rod
What is a Chemical Change? Definition & Examples
Chemical changes result in the formation of one or more new substances, involving a change in chemical properties and composition. Chemical bonds are broken and new ones form, often with noticeable energy changes (heat, light, sound), colour shifts, gas evolution, or precipitate formation—these clues help you spot chemical changes in JEE questions. Most chemical changes are irreversible by simple physical means.
- Rusting of iron (formation of Fe2O3)
- Burning of magnesium ribbon
- Digestion of food
- Souring of milk
- Combustion of fuels (like LPG)
Tabular Comparison: Difference Between Physical and Chemical Change
| Point of Comparison | Physical Change | Chemical Change |
|---|---|---|
| New Substance Formed | No new substance formed | New substance(s) created |
| Change in Chemical Composition | No change | Change occurs |
| Reversibility | Generally reversible | Usually irreversible |
| Energy Change | Minimal or none | Often significant (heat, light, sound) |
| Properties Affected | Physical properties only (shape, size, state) | Both physical and chemical properties |
| Clues/Observable Signs | No new smell/gas/precipitate; appearance/state only | Colour change, gas release, precipitate, temperature change |
| Examples (JEE) | Boiling, freezing, dissolving salt, cutting, magnetising | Rusting, combustion, fermentation, digestion, tarnishing |
Quickly scanning this table during revision helps answer “differentiate between physical and chemical changes in chemistry” for JEE questions. Try to write at least five points in the exam, always linking each to a clear property.
Examples of Physical and Chemical Changes (10+ Each)
- Physical Change Examples:
- Melting of ice
- Condensation of water vapour
- Breaking a pencil
- Stretching a rubber band
- Mixing sand and salt
- Cutting paper
- Crushing a can
- Dissolving common salt in water
- Magnetisation of iron
- Folding aluminium foil
- Chemical Change Examples:
- Rusting of iron nail
- Burning candle wax
- Respiration in living organisms
- Cooking of vegetables
- Electrolysis of water
- Baking a cake
- Vinegar reacting with baking soda
- Milk curdling
- Digestion of starch (in mouth and stomach)
- Rotting of fruits
If unsure in an exam, check: is the change only in form/state (physical), or does new composition or property arise (chemical)? Use typical settings: kitchen, laboratory, or material uses for context.
Physical vs Chemical Properties: Distinction
Physical properties are features observable/measurable without changing the substance’s identity: melting point, boiling point, density, magnetism, colour. In contrast, chemical properties describe how a substance interacts/reacts with others—reactivity with acids, oxidation tendency, flammability, stability, toxicity.
- Physical property: Melting point of ice, colour of copper
- Chemical property: Iron’s tendency to rust, gold’s inertness
- Physical change: Wax melting
- Chemical change: Wax burning
Properties indicate how a substance behaves. Changes show what actually happens, so property distinction is a favourite indirect question in JEE Chemistry.
Application, Mnemonics & Rapid Exam Recall
JEE Main frequently asks you to categorise a process or spot whether a change is physical or chemical. Practice with point-wise tables, always link clues (energy, substance change, reversibility). Use this simple mnemonic for recall:
- PCRC: Physical = Change in physical property; Chemical = New substance Created
- Physical changes do not alter the Compound's Recipe
- Chemical changes Create new Compounds
Memory Tip: If it’s reversible and no new product is formed, think “Physical.” If it’s irreversible or emits heat/light, or a gas/precipitate forms, think “Chemical.” Solve mocks and practice questions regularly for fastest exam recall.
Common Misconceptions Addressed
- Dissolving salt in water is a physical change—no new chemical substance forms, though ions disperse.
- Colour change alone does not always signal chemical change—sometimes it is just a physical phenomenon.
- Not all physical changes are easily reversible (e.g., breaking glass), but they never yield new substances.
- Burning a candle is both: wax melting (physical) and wax burning (chemical).
- State changes (solid ↔ liquid ↔ gas) are always physical, not chemical, unless new substances result.
You can apply these concepts in understanding processes in industries, environmental changes, and laboratory analysis. Visit trusted resources like Vedantu for more JEE-focused Chemistry breakdowns and to practice with high-yield questions and advanced comparison charts.
- Check Difference Between Mixture and Solution
- Get clarity on States of Matter for
Grasping the clear difference between physical and chemical change gives you an edge in the JEE Chemistry section and helps build logical analysis—crucial for high ranks. Practise regularly and check Vedantu’s detailed topic notes for accurate, exam-ready explanations.
FAQs on Difference Between Physical and Chemical Change Explained
1. What is the main difference between physical and chemical change?
The main difference between a physical change and a chemical change is that physical changes only alter the appearance or state of a substance, while chemical changes form new substances with different chemical properties.
Key differences include:
- Physical change does not change the chemical composition; chemical change does.
- Physical change is often reversible; chemical change is usually irreversible.
- No new substance is formed in a physical change; chemical change results in new substances.
2. Can you list 5 differences between physical and chemical changes?
Yes, here are 5 key differences between physical change and chemical change:
- Composition: Physical change does not alter substance composition; chemical change alters it.
- Reversibility: Physical changes are usually reversible; chemical changes are mostly irreversible.
- New Substance: No new substance forms in physical change; chemical change creates new substances.
- Energy Change: Physical changes may not involve energy change; chemical changes usually involve heat, light, or sound.
- Observable Signs: Physical change shows change in state or appearance; chemical change shows gas release, color change, precipitate formation, etc.
3. Provide examples of both types of changes in daily life.
Examples of physical and chemical changes in daily life include:
Physical Changes:
- Melting ice
- Boiling water
- Tearing paper
- Dissolving sugar in water
- Crushing a can
- Burning wood
- Rusting iron
- Cooking food
- Souring of milk
- Digestion
4. Is dissolving salt in water a physical or chemical change?
Dissolving salt in water is a physical change because the salt can be recovered by evaporation and no new substance is formed.
- The salt retains its chemical identity.
- No new compound is formed during the process.
- The change is reversible by simple physical means (evaporation).
5. How do I identify a chemical change in a reaction?
Chemical changes can be identified by signs such as:
- Formation of a new substance (gas, precipitate, or color change)
- Release or absorption of energy (heat, light, sound)
- Change in odor
- Irreversibility (cannot restore original substances easily)
- Bubbles or fizzing without heating
6. What are 10 examples each of physical and chemical changes?
10 examples of physical changes:
- Melting ice
- Boiling water
- Cutting vegetables
- Stretching rubber bands
- Breaking glass
- Freezing juice
- Crushing salt crystals
- Dissolving sugar in tea
- Condensation of steam
- Evaporating alcohol
- Burning paper
- Rusting iron
- Cooking rice
- Rotting fruit
- Baking a cake
- Digesting food
- Souring milk
- Photosynthesis
- Lighting a firecracker
- Formation of curd
7. What are physical and chemical properties? How do they differ?
Physical properties are characteristics like color, melting point, shape, and state that can be observed without changing the substance's chemical identity. Chemical properties describe a substance's ability to undergo chemical reactions and form new substances.
Difference:
- Physical properties can be measured without changing composition.
- Chemical properties can only be observed during a chemical change.
- Examples: Physical—density, boiling point; Chemical—flammability, reactivity.
8. Why is burning a candle both a physical and chemical change?
Burning a candle shows both physical and chemical changes because:
- Physical change: Melting of wax (solid to liquid) is reversible and does not alter chemical structure.
- Chemical change: The wax burns, reacting with oxygen to create new substances like carbon dioxide and water vapor, which is irreversible.
9. Does every color change mean a chemical change has happened?
Not every color change indicates a chemical change. Some color changes (like heating copper to red hot) are physical, involving only state or temperature shifts, while others (like rusting iron) are true chemical changes involving new substance formation.
Always check for other signs of chemical change before concluding.
10. Can a physical change be irreversible?
Yes, some physical changes can be irreversible, like breaking a glass or chopping wood. Although the chemical composition remains the same, the process cannot easily be undone.
- Physical changes affect form, not composition.
- Irreversibility occurs if restoring original form is not practical.
