Chrominfo: Identification test of copper sulphate

Learn the identification tests of copper sulphate through a laboratory experiment or practical.

Aim:

To perform identification tests of copper sulphate on a given sample.

Reference: Indian Pharmacopoeia (IP) 2010

Requirements:

Glasswares and miscellaneous:

Test tube, measuring cylinder, pipette, glass rod, volumetric flask, beaker, dropper, rubber stopper, test tube stand, test tube holder, and balance, etc.

Chemicals:

Sodium sulphide (Na2S), barium chloride (BaCl2), sodium hydroxide (NaOH), stannous chloride (SnCl2), ammonia (NH3), hydrochloric acid (HCL), and iodine (I2), etc.

Procedure for identification of copper sulphate:

Test-1: Take about 50.00 mg of the substance pour in 05.00 ml of water. Then add 01.00 ml of prepared solution of sodium sulphide, by which black precipitate is formed.
Test-2: Take about 50.00 mg of the substance pour in 05.00 ml of water, and then add 01.00 ml of ammonia solution. The precipitate was solubilized in excess of NH3 on acquiring a dark blue color.
Test-3: Take about 50.00 mg of the substance pour in 05.00 ml of water, and then add 01.00 ml prepared solution of dilute NaOH, by which blue precipitate is formed. In excess reagent, the precipitate is insoluble, and when heated, the precipitate turns black.
Test-4: Take about 50.00 mg of the substance dissolved in 05.00 ml of water. Add prepared 01.00 ml of dilute hydrochloric acid and then 01.00 ml of barium chloride solution, a white precipitate is formed.
Test-5: Add 00.10 ml of prepared iodine solution to the suspension produced in test-D; the suspension stays yellow however is decolorized by adding SnCl2 solution dropwise. Boil the mixture, no colored precipitate forms.
Test-6: Take about 50.00 mg of the substance dissolved in 05.00 ml of water. Then add 02.00 ml of prepared solution of lead acetate produces a white precipitate that is soluble in C2H7NO2 solution and NaOH is produced.

Observations:

Test-1: The addition of sodium sulphide solution resulted in the formation of a black precipitate.
Test-2: The Initial addition of ammonia solution resulted in the formation of a blue precipitate, which was solubilized in excess of ammonia, resulting in a deep blue solution.
Test-3: A white precipitate is created when dilute HCL and barium chloride solution are added.
Test-4: A yellow color was formed by adding iodine solution to the suspension, which is obtained in test 3. The addition of stannous chloride solution decolorized the color. Even after boiling the solution, the colored precipitate was not obtained.
Test-5: A white precipitate is formed by adding lead acetate to the test solution. After adding ammonium acetate and NaOH, the precipitate was solubilized.

Results:

The given sample complies with the tests 1 / 2 / 3 / 4 / 5 / 6 and does not comply with the tests 1 / 2 / 3 / 4 / 5 / 6 for the identification of copper sulphate as per IP 2010.

It suggests that the given sample is of ………………………...