Chemical vs Physical Changes Flashcards

Grade 5 · Science · Flashcards

Review key terms and examples to master the difference between chemical and physical changes.

Flashcards

Physical Change
A change that alters the size, shape, or state of matter WITHOUT creating a new substance. Examples: cutting, bending, melting, dissolving.
Chemical Change
A change that produces one or more new substances with different properties. Examples: burning, rusting, cooking.
Signs of a Chemical Change
Gas bubbles, color change, precipitate forming, heat/light released, or an unusual smell — all suggest new substances formed.
Precipitate
A solid that forms when two liquids are mixed during a chemical reaction, sinking to the bottom of the container.
Reversible vs Irreversible
Physical changes are usually reversible (ice melts and can refreeze). Chemical changes are usually irreversible (ash cannot become wood again).
Burning Paper
Chemical change — paper reacts with oxygen to form ash, carbon dioxide, and water vapor; entirely new substances result.
Melting Chocolate
Physical change — chocolate changes state from solid to liquid, but the chocolate molecules remain the same.
Rusting Iron
Chemical change — iron + oxygen + water → iron oxide (rust), which has completely different properties than iron.
Mixing Baking Soda and Vinegar
Chemical change — produces carbon dioxide gas (bubbles), water, and a salt; new substances are formed.
Cutting Fruit
Physical change — shape and size change, but the fruit material itself is unchanged.
Reactant
The starting substance(s) that enter a chemical reaction before any change occurs.
Product
The new substance(s) formed after a chemical reaction takes place.
Law of Conservation of Mass
In any chemical or physical change, matter is neither created nor destroyed — the total mass of reactants equals the total mass of products.

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