Who this is for: Cambridge IGCSE Coordinated Science (0654) students who want physical and chemical changes — telling reactions apart from state changes — to become a reliable source of marks instead of a keyword-guessing exercise.
What query it owns: how to understand and revise physical and chemical changes in Cambridge IGCSE Coordinated Science.
Why this is safe: this page owns the physical-and-chemical-changes revision-guide angle, while Tutopiya’s Physical And Chemical Changes subtopic page owns the learning resource and the free Physical And Chemical Changes quiz owns the practice.

Not every change in a substance is a chemical reaction. Cambridge IGCSE Coordinated Science (0654) expects you to distinguish physical changes — same substance, different state or form — from chemical changes — new substances formed. This guide links each type to the observations examiners reward.

Key takeaways

• A physical change does not form a new substance (e.g. melting, boiling, dissolving).
• A chemical change forms new substances (e.g. burning, rusting, neutralisation).
• Signs of chemical change include colour change, gas given off, temperature change and precipitate formed — but these alone do not prove a chemical change.
• Reversible physical changes (melting/freezing) differ from irreversible chemical changes (burning).
• Energy is taken in or given out in both types, but chemical changes involve breaking and making bonds.

What are physical and chemical changes in Cambridge IGCSE Coordinated Science?

A physical change alters the appearance or state of a substance without changing its chemical identity — ice melting to water is still H₂O. A chemical change produces one or more new substances with different properties — iron rusting forms iron oxide. Examiners often give everyday examples and ask you to classify them, or to explain why a change is physical or chemical.

You can read the full explanation, examples and notes on Tutopiya’s Physical And Chemical Changes subtopic page before you attempt questions.

Physical vs chemical change — core comparison

Feature	Physical change	Chemical change
New substance formed?	No	Yes
Reversible?	Often yes	Usually no
Examples	Melting, boiling, dissolving, crushing	Burning, rusting, fermentation, neutralisation
Chemical formula	Unchanged	Changed

Common examples — how to classify them

Change	Type	Reason
Ice melting	Physical	Still water (H₂O); no new substance
Paper burning	Chemical	Ash and gases — new substances
Dissolving sugar in water	Physical	Sugar molecules remain; can be recovered by evaporation
Iron rusting	Chemical	Iron oxide formed — new substance
Magnesium burning	Chemical	Magnesium oxide formed
Crushing chalk	Physical	Same substance, smaller pieces

Physical and chemical changes in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical change stem
State whether	Classify as physical or chemical	”State whether boiling water is a physical or chemical change.”
Explain	Justify classification	”Explain why rusting is a chemical change.”
Give an example	Provide a valid instance	”Give an example of a reversible physical change.”
Describe observations	List what you would see	”Describe what you would observe when magnesium burns.”

Worked exam-style stems (how to answer the wording)

1. “State whether melting ice is a physical or chemical change. Explain your answer.” Physical — the substance is still water (H₂O); only the state has changed from solid to liquid. Mark-scheme reward: no new substance and state change.
2. “Explain why the rusting of iron is a chemical change.” A new substance (iron oxide / rust) is formed with different properties from iron. Reward: new substance formed.
3. “Give two observations that suggest a chemical change has occurred.” Any two from: colour change, gas evolved, temperature change, precipitate formed, light emitted. Reward: two valid observations (note: these suggest but do not alone prove chemical change).

Test yourself with the Physical And Chemical Changes quiz once you can classify changes without hesitation.

How physical and chemical changes connect to the rest of Coordinated Science

This topic leads into Elements, Compounds And Mixtures and underpins all of chemistry — every reaction is a chemical change. It also links to energy changes in reactions. The Cambridge IGCSE Coordinated Science resource hub links every Atoms, Elements And Compounds subtopic.

Common mistakes students make

• Thinking dissolving is always chemical (usually physical if the solute can be recovered).
• Using boiling as evidence of a chemical change (boiling water is physical).
• Saying a colour change proves a chemical change (some physical changes show colour change too).
• Confusing condensation (physical) with a chemical reaction.
• Forgetting that crushing or cutting is physical — same substance, different size.

When you need more support

If physical vs chemical change questions keep costing marks, work through the Physical And Chemical Changes quiz, then get focused help from a Cambridge IGCSE Coordinated Science tutor.

Frequently asked questions

Is physical and chemical changes hard in Coordinated Science? The key test is simple — ask whether a new substance formed. Marks are lost when students rely on observations alone without checking for new substances.

Is dissolving a physical or chemical change? Usually physical — the solute can often be recovered unchanged by evaporation, showing no new substance formed.

What is the difference between melting and burning? Melting is physical (same substance, state change); burning is chemical (new substances such as ash and gases form).

How do I revise physical and chemical changes effectively? Classify ten everyday examples from memory, explain each using “new substance formed or not”, then take the Physical And Chemical Changes quiz.

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