Worksheet on identifying physical and chemical changes and properties with examples.

Let’s go step by step to classify each item as a chemical change (cc), chemical property (cp), physical change (pc), or physical property (pp).

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First, remember the definitions:

- Physical Property (pp): Something you can observe or measure without changing what the substance is. Examples: color, smell, melting point, density.

- Chemical Property (cp): Describes how a substance reacts with other substances — it tells you what kind of chemical changes it can undergo. Examples: flammability, reactivity with acid.

- Physical Change (pc): A change in form or state, but not in identity. The substance is still the same after the change. Examples: melting ice, tearing paper.

- Chemical Change (cc): A change that produces new substances. You can’t easily reverse it. Signs include: color change, gas produced, heat/light given off, precipitate formed. Examples: burning wood, rusting iron.

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Now let’s go one by one:

1. Heat conductivity → This is about how well something conducts heat — no new substance made → pp

2. Silver tarnishing → Silver reacts with sulfur in air to make black silver sulfide → new substance → cc

3. Sublimation → Solid turns directly to gas (like dry ice) — still the same substance → pc

4. Magnetizing steel → Steel becomes magnetic, but it’s still steel → pc

5. Length of metal object → Just measuring size — doesn’t change what it is → pp

6. Melting ice → Ice becomes water — still H₂O → pc

7. Exploding dynamite → Makes gases and heat — new substances formed → cc

8. Combustible → Means “can burn” — describes ability to react → cp

9. Water freezing → Liquid to solid — still water → pc

10. Wood burning → Makes ash, smoke, CO₂ — new substances → cc

11. Acid resistance → How well something resists reacting with acid → describes behavior in reaction → cp

12. Brittleness → Breaks easily — physical trait, no new substance → pp

13. Milk souring → Bacteria turn lactose into lactic acid — new substance → cc

14. Baking bread → Yeast makes CO₂, proteins denature — new substances and irreversible → cc

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✔ Final Answers:

1. pp
2. cc
3. pc
4. pc
5. pp
6. pc
7. cc
8. cp
9. pc
10. cc
11. cp
12. pp
13. cc
14. cc