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| Interesting Activities -2 |
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| Take a herbaceous plant and cut it into small pieces. Place them in a porcelain crucible in an oven at 100oC and dry overnight. The dried plant material is then heated to approximately 600oC in a muffle furnace or over a burner till it is changed to a greyish white ash. Cool the ash. Dissolve it in 20-50 ml of 2-5% acetic acid or HCl. The solution may be heated if needed. Small quantities of ash solution (a few drops or 1 ml) are taken for testing the elements. |
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| 1. Take 2 ml of solution. |
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| 2. Add 2 ml of perchloric acid. |
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| Observation |
| White precipitate appears. |
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| 1. Add a few drops of sodium cobalt nitrite solution into the ash solution. |
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| 2. Shake and slowly and pour 3 ml of 95% alcohol. |
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| Observation |
| Yellow precipitate is formed. |
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| 1. Take 3 ml of ash solution. |
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| 2. Add a few drops of 50% sulphuric acid. |
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| Observation |
| White precipitate of calcium sulphate appears in the solution. |
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| 1. Take 2 ml of ash solution. |
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| 2. Add a few drops of saturated ammonium oxalate solution and shake. |
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| Observation |
| A white precipitate indicates the presence of calcium. |
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| 1. Take 2 ml of ash solution. |
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| 2. Mix a few drops of 2% potassium ferrocyanide. |
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| 3. Add a drop of 5% HCl. |
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| Observation |
| A deep blue colour indicates iron. |
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| 1. Take 3 ml of ash solution. |
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| 2. Add a few drops of 20% ammonium thiocyanate. |
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| 3. Shake and add 2 ml of dil. HCl. |
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| Observation |
| Slight pink colour indicates iron. |
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| 1. Take 2 ml of ash solution. |
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| 2. Add 5-10 drops of ammonium molybdate solution. (1 g of ammonium molybdate in 10-15 ml of nitric acid). |
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| Observation |
| A yellow precipitate indicates phosphorus. |
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| 1. Take 2 ml of ash solution. |
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| 2. Add 5-10 drops of 2-5% acidic solution of ammonium molybdate. |
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| 3. Shake and add 2-4 drops of stannous chloride solution. |
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| Observation |
| The solution turns blue indicating the presence of phosphorus. |
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| 1. Take 2 ml of ash solution. |
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| 2. Add a few drops of magnesia reagent (0.05 g ammonium chloride + 0.1 g sodium phosphate + 2.5 ml ammonia + 100 ml of distilled water). |
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| Observation |
| White precipitate appears indicating magnesium. |
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| 1. Take 2 ml of ash solution. |
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| 2. Add a few drops of 5% NaOH solution. |
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| 3. Shake and add 2-3 drops of titan yellow (0.15% titan yellow in 75% alcohol). |
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| Observation |
| A deep orange colour indicates magnesium. |
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| 1. Take 2 ml of ash solution. |
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| 2. Add a few drops KOH solution. |
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| 3. Add a few drops of manganese reagent (0.05 g of benzedine in 100 ml of 10% acetic acid) to test solution. |
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| Observation |
| A blue colour indicates manganese. |
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| 1. Take 2 ml of ash solution. |
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| 2. Add 2-3 drops of 7% barium chloride. White precipitate appears. |
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| 3. Shake and add 4 drops of 25% acetic acid. |
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| Observation |
| Observation of white precipitate indicates that sulphur is present. |
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