📖 Theory & Concepts ▼

1. Physical vs Chemical Changes

Property Physical Change Chemical Change
New substance Not formed Formed
Reversibility Usually reversible Usually irreversible
Energy change Small Large (heat/light)
Composition Unchanged Changed
Example Melting ice Burning Mg ribbon

2. Signs of Chemical Change

  • 🎨 Color change — CuSO₄ blue → white
  • 💨 Gas evolution — CO₂ from vinegar + soda
  • 🔥 Heat/Light — Mg burns with bright light
  • ⬇️ Precipitate — Solid formed in solution
Did you know? Copper sulphate pentahydrate (CuSO₄·5H₂O) loses its blue color when heated because the water molecules responsible for the color are released as steam!
⚠️ Safety First ▼
  • Burning magnesium gives an intense, UV-rich white light — never stare directly at it; view it briefly and at an angle to protect your eyes.
  • Hot apparatus — the test tube and residue stay hot after heating copper sulphate. Use a test-tube holder and let everything cool before touching.
  • Bunsen burner — tie back long hair, keep the bench clear of flammables, and return to the luminous (safety) flame when not heating.
  • Vinegar + baking soda releases CO₂ gas — use an open/loose container so pressure cannot build up; the vapour and acid mildly irritate the eyes.
  • Copper sulphate is harmful if swallowed and irritates skin and eyes — never taste any chemical, wash your hands, and put copper waste in the labelled heavy-metal container.
  • Wear safety goggles for every experiment.

🎯 Objective

To perform various reactions and classify them as physical or chemical changes by observing:

  • Color change
  • Gas evolution
  • Temperature change
  • Formation of precipitate
  • Reversibility of the change
Select Experiment
> Click "Heat" to start heating the blue copper sulphate crystals.
Action Feedback
CuSO₄·5H₂O (Blue crystals)

🔮 Predict before you experiment

Lock a prediction to unlock the Heat action. Change experiment and you predict again.

Key Concepts

Physical Change
No new substance formed. Reversible. No change in composition.
Chemical Change
New substance formed. Usually irreversible. Change in composition.
Lab Notebook
Observations will appear here...