Ni-DMG complex - B Sc Inorganic Practicals PDF

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B Sc Inorganic Practicals...

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OBJECT: To prepare Ni-DMG complex. REAGENTS AND APPARATUS USED: Nickel ammonium sulphate, dil.HCl, dimethyl glyoxime, dil. Ammonia THEORY: Nickel is precipitated by the addition of an ethanolic solution of dimethyl glyoxime to a hot, faintly acidic solution of nickel salt and then adding a slight excess of aqueous ammonia solution.

PROCEDURE: Weigh out accurately 0.3-0.4g of pure nickel ammonium sulphate and dissolve it in water. Add 5ml of dil. HCl and dilute to 200ml. Heat to 70-80°C, add a slight excess of dimethyl glyoxime and immediately add dilute ammonia solution dropwise, directly to the solution in slight excess. Allow to stand on steam bath for 20-30 min. and test the solution for complete precipitation when the red precipitates have settled out. Allow the precipitate to stand for 15 min. Filter the cold solution through a pre-weighed sintered glass crucible or porcelain filtering crucible. Wash the precipitate with cold water until free from chloride and dry it at 110-120°C for about 30 min. Allow to cool in a desiccator and weigh. RESULT: (i) Physical state:………… (ii) Yield:…………..g. PRECAUTIONS: 1. DMG must be added in a slight excess to the solution. 2. Addition of ammonia solution should directly be to the solution, not through the wall of the beaker. 3. Complete precipitation must be checked. 4. Digestion of the precipitates must be done for appropriate time. 5. Washing of the precipitates should be done in small lots. 6. Ammonia is extremely irritating. 7. Always wear goggles and gloves.

Ni(HDMG)2 or Ni-DMG complex...