📖 Theory & Concepts▼

Sublimation

PropertyDetails
DefinitionDirect conversion of solid → gas without passing through liquid state
Reverse ProcessDeposition (gas → solid)
Sublimable SubstancesAmmonium chloride, camphor, naphthalene, iodine, dry ice
UseSeparating sublimable solid from non-sublimable impurities

Key Concepts

  • SublimationWhen ammonium chloride (NH₄Cl) is heated, it sublimes — goes directly from solid to vapour. The vapour deposits back as pure solid on a cool surface.
  • Separation PrincipleThe non-sublimable impurity (like sand or salt) remains in the dish, while the sublimable solid collects on the inverted funnel as pure crystals.
Did you know? Dry ice (solid CO₂) sublimes at −78.5°C — that's why it creates fog without leaving any liquid!

🎯 Objective

To separate ammonium chloride from a mixture of ammonium chloride and common salt using sublimation.

Procedure
1

Take mixture of NH₄Cl and NaCl in a china dish.

2

Place an inverted funnel over the dish.

3

Plug the stem of the funnel with cotton wool.

4

Heat the dish gently on a tripod stand.

5

Observe NH₄Cl vapours depositing on the funnel as white crystals.

Sublimation Experiment
Cotton wool China Dish Inverted Funnel
Lab Journal
Waiting for experiment...
Sublimate ---
Residue ---