📖 Theory & Concepts ▼

1. Mixture vs Compound

Property Mixture (Fe + S) Compound (FeS)
Composition Variable ratio Fixed ratio (1:1)
Separation Physical methods Chemical methods only
Magnetic Property Iron attracted No attraction
CS₂ Solubility Sulphur dissolves Insoluble
Dilute HCl H₂ gas (odorless) H₂S gas (rotten egg)

2. Key Concepts

  • Physical Change Mixing iron and sulphur is a physical change — components retain their properties and can be separated by physical means (magnet, CS₂).
  • Chemical Change Heating the mixture causes a chemical reaction. A new substance (FeS) is formed with entirely different properties.
  • Exothermic Reaction Fe + S → FeS + Heat
    The reaction releases energy, causing the mixture to glow.
Did you know? Iron Sulphide (FeS) is called fool's gold because of its metallic luster, though it's actually black when freshly made!
⚠️ Safety First ▼
  • Heating iron + sulphur is strongly exothermic and gives off choking sulphur dioxide (SO₂) fumes — work in a fume cupboard and stop heating once the glow starts to spread (the reaction then continues on its own).
  • Carbon disulphide (CS₂) is extremely flammable and toxic — keep it well away from any flame and use it only in a fume cupboard.
  • Dilute HCl on iron sulphide releases toxic hydrogen sulphide (H₂S, rotten-egg smell) — waft gently to smell, never inhale directly; fume cupboard.
  • Hot / glowing apparatus — use tongs and let everything cool before touching; never handle the glowing mass.
  • Iron and sulphur powders irritate the eyes and airways — avoid raising dust and wash your hands afterwards.
  • Wear safety goggles throughout.

🎯 Objective

To prepare a mixture and a compound using Iron filings and Sulphur powder and distinguish between them on the basis of:

  • Appearance (Homogeneity)
  • Magnetic properties
  • Behavior towards solvents (CS₂)
  • Reaction with acids (HCl)

🔮 Predict before you heat

Mix the elements, then lock a prediction to unlock the Heat action.

Procedure Guide
> Add Iron Filings and Sulphur Powder to the watch glass to begin.
Action Feedback
Empty Dish
Watch Glass (Empty)

Testing Tools

Lab Notebook
Observations will appear here...