Understanding the Properties
* Iodine: A solid, dark purple/black element that sublimes (turns directly from solid to gas) when heated.
* Ammonium chloride (NH₄Cl): A white, crystalline solid that is soluble in water.
* Barium chloride (BaCl₂): A white, crystalline solid that is soluble in water.
Separation Procedure
1. Sublimation of Iodine:
* Principle: Iodine's ability to sublime at relatively low temperatures.
* Method: Heat the mixture gently in a fume hood or a well-ventilated area. The iodine will turn directly into a violet vapor and can be collected by condensation on a cold surface (like a petri dish with ice water).
2. Dissolving in Water:
* Principle: Ammonium chloride and barium chloride are both soluble in water, while iodine is not.
* Method: Add water to the remaining solid mixture (the residue after sublimation). Stir thoroughly to dissolve the ammonium chloride and barium chloride.
3. Filtration:
* Principle: Separating insoluble solids from a liquid solution.
* Method: Filter the solution through a filter paper. The iodine will remain as a solid on the filter paper.
4. Evaporation:
* Principle: Ammonium chloride and barium chloride are both soluble in water, but their solubility decreases as the temperature drops.
* Method: Carefully heat the filtrate (the solution that passed through the filter paper) on a hot plate or Bunsen burner. As the water evaporates, the ammonium chloride and barium chloride will start to crystallize.
5. Recrystallization: (Optional)
* Principle: Further purification of the ammonium chloride and barium chloride.
* Method: Dissolve the crystallized ammonium chloride and barium chloride in a minimum amount of hot water. Allow the solution to cool slowly. The crystals will reform with increased purity as impurities are left in solution.
Final Separation:
* You'll have obtained:
* Pure iodine on the filter paper
* Ammonium chloride crystals
* Barium chloride crystals
Safety Precautions
* Fume Hood: Sublimation of iodine should be done in a fume hood to prevent inhaling the vapor.
* Gloves: Wear gloves when handling iodine as it can stain skin.
* Ventilation: Ensure proper ventilation throughout the process.
* Barium Chloride: Barium chloride is toxic. Avoid contact with skin or eyes.
Important Note: This separation method assumes a relatively small amount of mixture. For larger amounts, you might need to adjust the scales of the equipment and procedures.
