Ammonia is added khổng lồ solutions of cobalt, nickel, and copper 2+ cations. First formation of the hydroxide precipitate is seen, then of the ammonia complex.Bạn sẽ xem: Cu(Oh)2 + Nh3 = Cu(Nh3)4(Oh)2
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| Co2+ + NH4OH → Co(OH)2(s) | blue ppt. (gives green mixture) |
| Cu2+ + NH4OH → Cu(OH)2(s) | blue ppt. |
| Ni2+ + NH4OH → Ni(OH)2(s) | green gel |
| Co(OH)2(s) + 6NH3 → Co(NH3)62+(aq) | brown complex |
| Cu(OH)2(s) + 4NH3 → Cu(NH3)42+(aq) | dark blue complex |
| Ni(OH)2(s) + 6NH3 → Ni(NH3)62+(aq) | blue complex |
To Conduct Demonstration
Pour 0.1M solutions of Cu2+, Co2+, and Ni2+ into pairs of labeled beakers (to a depth of 1/2") on an overhead projector or document projector, or into 200mm chạy thử tubes (to a depth of 1") in a lighted rack.Add 3M or 6M NH4OH drop wise while stirring with the stir rod lớn one beaker or chạy thử tube of each pair. The solutions will become cloudy and change color due to lớn the precipitation of metal hydroxides.Add 15M NH4OH with stirring khổng lồ the same beaker or test tube. The precipitates will dissolve and darkly colored ammonia complexes will form.Xem thêm: A) Viết Phương Trình Điện Li Của Fe2 So4 3 + Naoh, Viết Phương Trình Điện Li Của Các Chất
(Cobalt requires 6 times the cation volume to khung the complex.) Use the other beakers or test tubes as references. Use watch glasses over the beakers or crystallizing dishes to contain the ammonia fumes.
Safety