Preparation of Inorganic Compounds

A. Preparation of pure sample of Ferrous ammonium sulphate (Mohr’s salt) [FeSO4.(NH4)2SO4.6H2O]

Materials Required

  • Ferrous sulphate
  • Ammonium sulphate
  • Dil. Sulphuric acid
  • Ethyl alcohol
  • Distilled water
  • Beakers
  • China dish
  • Funnel
  • Glass rod
  • Tripod stand
  • Wire gauze
  • Burner
  • Wash bottle 
  • Measuring jar
  • Electronic balance

Procedure

Real Lab Procedure

  1. We’ll first take 7g ferrous sulphate 3.5g ammonium sulphate in a clean 250ml beaker.
  2. To this add about 2-3ml of dil.sulphuric acid to prevent the hydrolysis of ferrous sulphate.
  3. In another beaker, boil about 20ml of water for 5 minutes.
  4. Add the boiling hot water to the contents in the first beaker in small quantities at a time.
  5. Stir the contents of the beaker with a glass rod until the salts have completely dissolved.
  6. Filter the solution into a china dish.
  7. Now heat the solution in the china dish until its crystallisation point is reached. Then transfer the solution into a crystallising dish and keep it undisturbed.
  8. On cooling, crystals of Mohr’s salt separate.
  9. Decant the mother liquor and wash the crystals with a small quantity of alcohol and then dry the crystals by placing them between filter paper pads.
  10. Find the weight of the crystals.

Observations

  1.  Weight of the crystals obtained = ....g
  2.  Colour of the crystals = ....
  3.  Shape of the crystals = ....

B. Preparation of pure sample of potash alum (Fitkari) [K2SO4.Al2(SO4)3.24H2O]

Materials Required

  • Potassium sulphate
  • Aluminium sulphate
  • Dil. Sulphuric acid
  • Distilled water
  • Beakers
  • China dish
  • Funnel
  • Glass rod
  • Tripod stand
  • Wire gauze
  • Burner
  • Wash bottle
  • Measuring jar
  • Electronic balance

Procedure

Real Lab Procedure

  1. Take 2.5g potassium sulphate crystals in a clean beaker.
  2. To this add 20ml of distilled water and stir using a glass rod until the crystals completely dissolve.
  3. Take 10g aluminium sulphate in another beaker.
  4. Add about 20ml of distilled water and 1ml of dil.sulphuric acid to it.
  5. Heat the contents of the beaker for about 5 minutes.
  6. Mix the two solutions in a china dish.
  7. Heat the solution in the china dish for some time to concentrate it to the crystallisation point.
  8. Transfer the solution into a crystallising dish and do not disturb it.
  9. On cooling crystals of potash alum separate.
  10. Decant the mother liquor and wash the crystals with a small quantity of ice-cold water.
  11. Dry the crystals by placing them between filter paper pads.
  12. Find  the weight of the crystals.

Observations

  1. Weight of the crystals obtained = ....g
  2. Colour of the crystals = ....
  3. Shape of the crystals = ....

C. Preparation of the complex Potassium trioxalatoferrate (III) {K3[Fe(C2O4)3].3H2O}

Materials Required

  • Ferric chloride
  • Hydrated oxalic acid
  • Hydrated potassium oxalate
  • Potassium hydroxide
  • Distilled water
  • Beakers
  • China dish
  • Funnel
  • Glass rod
  • Tripod stand
  • Wire gauze
  • Burner
  • Wash bottle 
  • Measuring jar
  • Electronic balance

Procedure

Real Lab Procedure

  1. Take 3.5g of anhydrous ferric chloride in a250ml beaker and dissolve it in 50ml water.
  2. In another beaker dissolve 4g of potassium hydroxide in 50ml water.
  3. Add potassium hydroxide to ferric chloride solution in small proportions while stirring constantly.
  4. Filter the precipitate of ferric hydroxide formed through a Buchner funnel and wash it with distilled water.
  5. In another beaker, take 4g of hydrated oxalic acid and 5.5g of hydrated potassium oxalate.
  6. Add about 100ml of water and stir thoroughly to get a clear solution.
  7. Add the freshly prepared ferric hydroxide precipitate in small amounts to the above solution while stirring constantly until the precipitate dissolves.
  8. Filter the above solution into a china dish and heat over a sand bath until its crystallisation point is reached.
  9. Place the china dish in a beaker full of cold water and keep it aside for filtration.
  10. Cover the china dish with a piece of black paper because the complex is sensitive to light.
  11. Decant the mother liquor, wash the crystals with a small amount of ethyl alcohol and dry them between the folds of filter paper.
  12. Find  the weight of the crystals.

Observations

  1. Weight of the crystals obtained = ....g
  2. Colour of the crystals = ....

Simulator Procedure (as performed through the Online Labs)

You can select a compound from ‘Select the compound’ drop down list.

Ferrous ammonium sulphate

  • Drag the watch glass to the beaker to transfer 7 g ferrous sulphate into it.
  • Drag the watch glass to the beaker to add 3.5 g ammonium sulphate to the beaker containing ferrous sulphate.
  • Drag the measuring jar to the beaker to pour 3 ml dil. H2SO4 into it.
  • Click on the “Next” button to go to the next process.
  • Drag the beaker to pour 20 ml hot water into the beaker containing ferrous sulphate and ammonium sulphate.
  • Drag the glass rod to the beaker to stir the contents of the beaker.
  • Drag the beaker to the funnel to filter the solution into the china dish.
  • Click on the “Next” button to go to the next process.
  • Click on the knob of the burner to turn it on.
  • Drag the glass rod to the china dish to stir the solution.
  • Drag the china dish to the crystallising dish to transfer the solution.
  • Drag the watch glass to the crystallising dish to cover the dish with it.
  • Drag the crystallising dish to the cold water trough to place the dish in it.
  • Wait for some time to cool the solution.
  • Click on the “Next” button to go to the next process.
  • Drag the crystallising dish to the beaker to decant the mother liquor into it.
  • Drag the bottle to the crystallising dish to pour ethyl alcohol into it.
  • Drag the crystallising dish to shake it and wash the crystals with alcohol.
  • Drag the crystallising dish to the filter paper to transfer the crystals.
  • Drag the other filter paper to the filter paper containing crystals to dry the crystals.
  • Drag the filter paper to the watch glass to transfer the crystals into it.
  • Click on the inference icon to see the inference.
  • To redo the experiment, click on the ‘Reset’ button.

Note: Click on the ‘HELP’ button to see the instructions.

 Potash alum

  • Drag the watch glass to the beaker to add 2.5 g potassium sulphate into 20 ml distilled water.
  • Drag the watch glass to the beaker to add 10 g aluminium sulphate into 20 ml distilled water.
  • Drag the measuring jar to the beaker to pour 1 ml dil. dil. H2SO4 into it.
  • Click on the “Next” button to go to the next process.
  • Drag the beaker to the burner to place it over the wire gauze and heat aluminium sulphate solution.
  • Drag the beaker to the china dish to transfer aluminium sulphate solution into it.
  • Drag the beaker containing potassium sulphate solution to the china dish to transfer the solution into it.
  • Click on the “Next” button to go to the next process.
  • Click on the knob of the burner to turn it on.
  • Drag the glass rod to the china dish to stir the solution.
  • Drag the china dish to the crystallising dish to transfer the solution.
  • Drag the watch glass to the crystallising dish to cover the dish with it.
  • Drag the crystallising dish to the cold water trough to place the dish in it.
  • Wait for some time to cool the solution.
  • Click on the “Next” button to go to the next process.
  • Drag the crystallising dish to the beaker to decant the mother liquor into it.
  • Drag the bottle to the crystallising dish to pour ethyl alcohol-cold water mixture into it.
  • Drag the crystallising dish to shake it and wash the crystals with alcohol-cold water mixture.
  • Drag the crystallising dish to the filter paper to transfer the crystals into it.
  • Drag the other filter paper to the filter paper containing crystals to dry the crystals.
  • Drag the filter paper to the watch glass to transfer the crystals into it.
  • Click on the inference icon to see the inference.
  • To redo the experiment, click on the ‘Reset’ button.

Note: Click on the ‘HELP’ button to see the instructions.

Potassium trioxalatoferrate (III)

  • Drag the watch glass to the beaker to add 3.5 g ferric chloride into 50 ml distilled water.
  • Drag the watch glass to the beaker to add 4 g potassium hydroxide into 50 ml distilled water.
  • Drag the glass rod to the beaker containing potassium hydroxide to stir the contents of the beaker.
  • Drag the beaker to add potassium hydroxide solution to the beaker containing ferric chloride solution.
  • Click on the inference icon to see the inference.
  • Click on the “Next” button to go to the next process.
  • Drag the filter paper to the Buchner funnel to place it in the funnel.
  • Drag the beaker to the Buchner funnel to filter the contents of the beaker.
  • Click on the inference icon to see the inference.
  • Click on the “Next” button to go to the next process.
  • Drag the watch glass to the beaker to add 4 g hydrated oxalic acid into 100 ml distilled water.
  • Drag the watch glass to the beaker to add 5.5 g hydrated potassium oxalate to the beaker.
  • Drag the watch glass to the beaker to add ferric hydroxide precipitate into the solution of potassium hydroxide and oxalic acid.
  • Drag the beaker to the funnel to filter the solution into the china dish.
  • Click on the “Next” button to go to the next process.
  • Click on the knob of the burner to turn it on.
  • Drag the glass rod to the china dish to stir the solution.
  • Drag the china dish to the cold water trough to place the dish in it.
  • Drag the black paper to the cold water trough to cover the china dish with it.
  • Wait for some time to cool the solution in the china dish.
  • Click on the “Next” button to go to the next process.
  • Drag the bottle to the china dish to pour ethyl alcohol into it.
  • Drag the china dish to shake it and wash the crystals with ethyl alcohol.
  • Drag the china dish to the filter paper to transfer the crystals into it.
  • Drag the other filter paper to the filter paper containing crystals to dry the crystals.
  • Drag the filter paper to the watch glass to transfer the crystals into it.
  • Click on the inference icon to see the inference.
  • To redo the experiment, click on the ‘Reset’ button.

Note: Click on the ‘HELP’ button to see the instructions.

Precautions

  1. Do not concentrate the solution too much.
  2. To get large crystals, let the concentrated solution cool slowly and remain undisturbed.
  3. Do not heat the solution of ferrous sulphate and ammonium sulphate for a long time as it may oxidise ferrous ions to ferric ions.

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