Carrying out test tube reactions to identify transition metal ions in solution
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Measure samples of each unknown metal ion
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To the first test tube, add a few drops of sodium hydroxide solution
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add more sodium hydroxide solution until in excess
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To the second test tube, add a few drops of ammonia solution
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add more ammonia solution until in excess
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To the third test tube, add a few drops of sodium carbonate solution
| Metal-aqua ion | OH– (aq)/ NH3 (aq) |
XS OH–(aq) | XS NH3 (aq) | Na2CO3 (aq) |
| [Cu(H2O)6]2+ Blue solution |
[Cu(H2O)4(OH)2]
Blue precipitate |
No visible change | [Cu(H2O)2(NH3)4]2+
Deep blue solution |
CuCO3 Green-blue precipitate |
| [Fe(H2O)6]2+
Green solution |
[Fe(H2O)4(OH)2]
Green precipitate |
No visible change | No visible change | FeCO3 Green precipitate |
| [Al(H2O)6]3+
Colourless solution |
[Al(H2O)3(OH)3]
White precipitate |
[Al(H2O)2(OH)4]– Colourless solution |
No visible change | [Al(H2O)3(OH)3]
White precipitate, bubbles of CO2 |
| [Fe(H2O)6]3+
Yellow solution |
[Fe(H2O)3(OH)3] Brown precipitate |
No visible change | No visible change | [Fe(H2O)3(OH)3]
Brown precipitate, bubbles of CO2 |