ANDChemistry/Preparation of Tetraamminecopper(II)sulphate monohydrate

Preparation of Tetraamminecopper(II) sulphate monohydrate, [Cu(NH₃)₄]SO₄.H₂O

1. Weigh 2.5 g of copper(II) sulphate pentahydrate, CuSO₄.5H₂O using a weighing balance.
2. Transfer the salt to a conical flask and add 10 ml of distilled water. Stir the solution to get a clear light blue solution.
3. Add 8 mL of liquor ammonia, NH₃ to this solution. Shake well to get a clear deep blue solution.
4. To this deep blue solution add 8 mL of ethyl alcohol. A microcrystalline deep blue solid will be obtained.
5. Place the conical flask in a boiling water bath and place a rubber cork loosely in a tilted position on the mouth of the conical flask.
6. Heat the suspension without shaking the flask, till a clear deep blue solution is obtained again. (A change in colour from deep blue to light blue indicates decomposition of the product and loss of NH₃ from the solution. Don’t worry. Cool the flask and its contents and add NH₃ again till deep blue coloured solution or solid is obtained back)
7. Transfer the clear hot solution to a preheated beaker immediately and leave the beaker covered and undisturbed for 45 minutes to get long deep blue needle like crystals of the complex.
8. Filter the crystals carefully either using normal filtration or using suction. Wash the crystals using 2 mL of alcohol.
9. Dry the crystals by leaving on the filter paper for about an hour. (Do not keep on changing the filter paper containing the product. This results in loss of product. Change only the filter papers underneath). Record the yield of the product.
10. Seal the dried crystalline complex in a plastic packet labeled with your name and roll number.
11. Submit the sample to your teacher.

• Dr. Manisha Jain