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Difficulty: EasySublimation, Magnetization, and Centrifugation

A solid mixture consists of iron filings, ammonium chloride, and sodium chloride. Arrange the following laboratory steps in the correct chronological order to separate each component and isolate pure sodium chloride crystals.

  1. 1Pass a magnet through the dry solid mixture to extract the magnetic component.
  2. 2Heat the remaining mixture in an evaporating dish covered with an inverted funnel to collect the sublimated vapor.
  3. 3Add distilled water to the remaining solid, stir thoroughly, and filter the mixture.
  4. 4Evaporate the clear filtrate to dryness to obtain sodium chloride crystals.

Answer

The correct separation sequence is: 1. Remove iron filings using a magnet, 2. Sublimate ammonium chloride by heating, 3. Dissolve the residual salt in water and filter, 4. Evaporate the filtrate to collect sodium chloride crystals.
The correct order proceeds from dry physical removal to thermal transformation and finally solution-based separation. First, dry magnetization removes ferromagnetic iron filings without wetting the mixture. Second, thermal heating sublimates volatile ammonium chloride directly into gas, leaving non-volatile sodium chloride behind. Third, adding water dissolves sodium chloride, allowing filtration of insoluble residue. Finally, evaporating the filtrate recovers pure sodium chloride crystals.

Step-by-Step Solution

1
Separate magnetic iron filings from the dry solid mixture using a magnet.
Iron filings are isolated cleanly without interference from liquids.
Magnetization requires dry solid conditions to efficiently attract ferromagnetic materials.
2
Heat the remaining mixture under an inverted funnel to separate ammonium chloride.
Ammonium chloride sublimates into gas and deposits as a pure solid on the cool funnel walls.
Ammonium chloride sublimes easily, whereas sodium chloride has a very high melting and boiling point and remains unaffected.
3
Dissolve the leftover solid residue in distilled water and pass it through filter paper.
Sodium chloride dissolves to form an aqueous filtrate while any insoluble impurities stay on the filter paper.
Water acts as a solvent for sodium chloride to separate it from insoluble solid impurities.
4
Heat the aqueous filtrate until the water completely evaporates.
Pure sodium chloride crystals remain in the evaporating dish.
Evaporation removes the liquid solvent leaving behind the dissolved solute.

Key Concept

Sequential separation of mixtures utilizing magnetization, sublimation, dissolution, filtration, and evaporation based on physical properties.
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Topics

Sublimation, Magnetization, and Centrifugation