Chemical properties of iron

2.1. Place 5 drops of acids solutions into four test tubes: of 2 M hydrochloric, of 2 M nitric, of 1 M sulfuric and of concentrated sulfuric acids. Put some iron sawdust into each of the test tubes. Heat up the test tube with concentrated sulfuric acid. Then add 1 droplet of 0,5N potassium thiocyanate solution to each test tube. In what test tubes and how does the solution colour change? Give the equations of the relevant reactions, taking into account an opportunity of iron (ІІ) compounds formation.

2.2. Place 2-3 mls of concentrated nitric acid into a test tube and immerse in it well scraped soft steel plate. What can you observe? Then pull it out of the acid, wash out thoroughly with water and immerse in the test tube with 0,5N copper sulfate solution. For comparison, immerse other soft steel plate in the copper sulfate solution. Explain the phenomena, which are observed.

×2.3. Place 3-4 drops of 0,5N ammonium - iron (ІІ) sulfate solution (NH₄)₂SO₄×FeSO₄×6H₂O (Mohr's salt) into each of two test tubes and add by drops 2 M sodium hydroxide solution until precipitate forms. Add by drops 1 M hydrochloric acid solution into the first test tube. What occurs? Stir the precipitate into the second test tube with glass rod and leave it in a stand for some time. What can you observe? How and why did the colour of the precipitate into the second test tube change? Give the equations of the relevant reactions.

2.4. Place 4-6 drops of 0,5N iron (ІІІ) sulfate solution into a test tube and add 3-4 drops of 0,5N solution of sodium carbonate. What can you observe? Give the equations of the relevant reactions.

2.5. Place 3-4 drops of 0,5N just obtained iron (ІІ) sulfate solution into each of two test tubes and add 2-3 drops of 0,5N potassium hexacyanoferrate (ІІІ) solution K₃[Fe(CN)₆] into the first test tube, and the same amount of 0,5N potassium hexacyanoferrate (ІІ) solution K₄[Fe(CN)₆] into the other one. In what case does the discolouration of solution have place? Give the equations of the relevant reactions.

Place 3-4 drops of 0,5N iron (ІІІ) chloride solution into each of two test tubes and add 2-3 drops of 0,5N potassium hexacyanoferrate (ІІІ) solution K₃[Fe(CN)₆] into the first test tube, and the same amount of 0,5N potassium hexacyanoferrate (ІІ) solution K₄[Fe(CN)₆] into the other one. In what case had the solution discolouration taken place? Give the equations of the relevant reactions.

2.6. Place 3-4 drops of 0,5N iron (ІІІ) chloride solution into a test tube and add 2-3 drops of 0,5N potassium iodide solution. What can you observe? What properties does iron (ІІІ) show in this reaction? Give the equations of the relevant reactions.

2.7. Put 3-4 slices of sodium hydroxide, 4-5 drops of 0,5N iron (ІІІ) sulfate solution into a porcelain crucible and add 2 drops of bromine (carry out the experiment in a ventilating hood). Heat up the crucible cautiously. What can you observe? What colour do the solution have? Transfer the solution from the crucible to a test tube and add 1-2 drops of 0,5N barium chloride solution. What can you observe? Give the equations of the relevant reactions.

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