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13 Cards in this Set
- Front
- Back
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Colors of sulphide salts of Zn Mn Ni Co |
Zn white Mn flesh color Ni, Co black |
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What's the first step in group IV separation? |
Add 5 drops of dilute HCl to ppt and stir. Co and Ni will remain as ppt, Zn and Mn will dissolve as ZnCl2 and MnCl2 |
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Why we boil the solution containing ZnCl2 and MnCl2? |
The reaction with HCl produce H2S, which when boiled will evaporate so drive reactions to completion. ZnS ppt won't form later when NaOH is added |
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What to do with NiS and CoS before doing confirmation tests? |
Add concentrated HCl and trace KClO3. Boil until no more fumes. NiCl2 and CoCl2 along with S will be produced |
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Confirm Ni |
1 drop of dimethylglyoxime and add 50% NH4OH drop by drop until basic. Scarlet ppt confirms Ni |
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Confirm Co |
Add 3 crystals of KSCN, 6 drops of ether and amyl alcohol each. Shake to mix. Blue liquid in upper ether layer containing [Co(SCN)4]2- confirm Co |
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Why is amyl alcohol added for confirming Co? |
To prevent mixing of ether and aqueous layers |
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Confirm Mn |
Same procedure as the test in group III for Mn |
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How to separate Zn from Mn? |
Add dilute NaOH to solution containing ZnCl2 and MnCl2. Mn will ppt while Zn remain soluble |
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Confirm Zn |
Pass H2S, if white ppt appears Zn may be present. Centrifuge and discard solution. Add dilute HCl to dissolve ppt and add 1 drop of K4FeCN6. White ppt confirms Zn |
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How should we wash the ppt in the first step? |
Water and 1 drop of NH4OH |
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What are the reaction products of ZnS and MnS with HCl? |
ZnCl2 and MnCl2 with H2S. Boil reaction to expel H2S |
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What are the reaction products of NiS and CoS with HCl and KClO3? |
NiCl2 + H2O + S + KCl |
