Thermal Decomposition of Ammonium Chloride

Ammonium chloride, when heated, undergoes decomposition into hydrogen chloride and ammonia gasses, before reforming when cool. The process appears similar to sublimation and deposition.

1. Place a small amount of solid ammonium chloride in a china dish.
2. Cover the dish with an inverted funnel, ensuring the stem points upward.
3. Plug the funnel’s stem loosely with cotton wool to prevent rapid escape of vapors.
4. Heat the china dish gently using a burner or hot plate.
5. Observe white ammonium chloride vapors rising and redepositing as solid crystals on the cooler parts of the funnel.

SUBLIMATION of Ammonium chloride (NH₄Cl) - Basic Practical CHEMISTRY | Separation of Mixture - Science Sir:

Demonstrate Sublimation using ammonium chloride | 9th chemistry practical - Chemistry Plus:

📄 Thermal Decomposition of NH4C - Embibe: https://www.embibe.com/lab-experiments/thermal-decomposition-of-nh4cl/

• Use a test tube with ammonium chloride and heat the bottom, observing crystals forming at the cooler upper end.
• Compare the sublimation of ammonium chloride with iodine or naphthalene.
• Perform time-lapse photography to capture the deposition process.

• Wear safety goggles, gloves, and a lab coat.
• Perform the experiment in a well-ventilated area or fume hood; ammonium chloride vapors can be irritating.
• Avoid inhaling fumes and skin contact with the solid.
• Dispose of ammonium chloride residue safely according to laboratory waste guidelines.

• Why is heating ammonium chloride an example of sublimation? (It transitions directly from solid to gas without passing through the liquid phase.)
• Why do crystals form on the funnel? (The vapors cool and redeposit as solid ammonium chloride.)
• How does sublimation differ from evaporation? (Evaporation involves liquid to gas, while sublimation is solid to gas.)
• What other substances commonly show sublimation under laboratory conditions? (Iodine, dry ice, naphthalene.)