Estimation of Ni from the mixture of Ni2+ and Cu2+ solution
- Pipette 25 mL given solution quantitatively into a 200 or 250 mL beaker. Acidify the solution with 1-2 mL of conc. HCl, warm the solution and pass H2S carefully to precipitate copper sulfide (black ppt.) completely.
- Remove H2S by boiling the solution gently (test with lead acetate paper). Cool the solution to 70-800C.
- Add 30-35 mL of dimethylglyoxime(dmg) solution and immediately add dilute ammonium solution drop-wise with constant stirring until the precipitation(ppt) of the complex (red color ppt.) is complete and then in slight excess.
- Allow the mixture to stand on a steam bath for 20-30 minutes and test the solution for complete precipitation of Ni2+.
- Then allow the precipitate to stand for 1 hour, cooling at the same time. Filter the mixture through a sintered glass crucible that has been previously cleaned.
- Dried at 100-1200C and weighed after cooling in a desiccator. Wash the precipitate with cold water until free from chloride and sulfate and finally with a few mL of rectified spirit. Dry it at 100-1200C for about an hour, cool it in a desiccator and weigh. Repeat the process until constant weight is attained.
Hints for calculation: 1g complex = 0.2032g Ni
This post was submitted by
Md. Emon Ali
Department of Chemistry