Let’s go through each item one by one and decide if it’s a
chemical change or a
physical change.
Remember:
-
Physical change: The substance changes form (like shape, state) but is still the same stuff. No new substances are made.
-
Chemical change: A reaction happens — new substances are formed. Often you see color change, gas bubbles, heat, or smell.
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1.
Heating water into steam
→ Water turns from liquid to gas. It’s still H₂O. Just changed state.
✔ Physical change
2.
Milk going sour
→ Bacteria turn milk sugar into acid. Smells bad, tastes different — new stuff formed.
✔ Chemical change
3.
Dissolving sugar in water
→ Sugar disappears, but it’s still there — you can evaporate water and get sugar back.
✔ Physical change
4.
Iron rusting
→ Iron + oxygen → rust (iron oxide). New substance with different properties.
✔ Chemical change
5.
Hydrochloric acid and sodium hydroxide reacting and forming salt and water
→ Acid + base → salt + water. Classic chemical reaction. New products!
✔ Chemical change
6.
Digesting food into nutrients
→ Your body breaks down food using enzymes — makes new molecules your body can use.
✔ Chemical change
7.
Melting ice into water
→ Solid to liquid. Still H₂O. Just melted.
✔ Physical change
8.
Acid rain dripping onto limestone and making carbon dioxide gas
→ Acid reacts with limestone (calcium carbonate) → CO₂ gas + other stuff. Gas = sign of chemical change.
✔ Chemical change
9.
Breaking a glass into pieces
→ Glass is still glass — just smaller pieces. Shape changed, not identity.
✔ Physical change
10.
Hydrogen peroxide decomposing into oxygen gas and water
→ One substance breaks into two new ones: O₂ gas and H₂O. Definitely chemical.
✔ Chemical change
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Final Answer:
1. Physical
2. Chemical
3. Physical
4. Chemical
5. Chemical
6. Chemical
7. Physical
8. Chemical
9. Physical
10. Chemical
Parent Tip: Review the logic above to help your child master the concept of worksheet on chemical and physical properties and changes.
