Sa Separation and Detection ofzinc dish and careful Place the supermatant from P
ID: 533433 • Letter: S
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Sa Separation and Detection ofzinc dish and careful Place the supermatant from Procedure 4 in an evaporating HN evaporate to dryness using a burner flame. (CAUTION: Concentrated with it, can cause severe burns Avoid contact with you come in cont t drops of 16 M the area with five (Yg HNO, and heat again until no more fumes are observed. are removing NH4' ions that would interfere with the tests for MR2. Dissolve the residue in five drops of6 MHCI. Add 10 drops of distilled water to the HCI solution and transfer it to a small test tube. out the evaporating dish with 10 drops of distilled water and add the wash to the solution. Add 3 MNaoH until the solution is basic to litmus; and reserve the precipitate for Procedure 5b. Wash the precipitate with 10 drops of distilled water and add the washings to the supernatant. Add three drops of K.[Fe(CN)6] to the supernatant and acidify with 6 M HCl; a gray-blue colora- tion or precipitate ofzn,K2[FedcNeb confirms the presence of zn2" ions. 5b Separation and Detection of Nickel (CAUTION: Concentrated NH, has a strong irritating odor and causes severe burns. Avoid inhaling it. you come in contact with it, immediately wash the area with copious amounts of water.) Add five drops of distilled water and five drops of 15 M NH3 to the precipitate from Procedure 5a; centrifuge and reserve the precipitate for Procedure 5e. Wash the precipitate with 10 drops of distilled water and add the wash to the supematant. Add one drop of dimethylglyoxime solution to the s a strawberry red upennatant: precipitate of Nico4H1N202) confirms the presence of Ni ions. 5c Detection of Magnesium If Ni ns were confirmed in Procedure 5b, add 15 M NH1 to the precipitate you saved from Procedure 5 until a negative result for Ni is obtained. Dis- the precipitate in two drops of 6 Hcl. add two drops of Magnesium reagent M until solution is basic. A "blue lake confirms the presence of Mg2 theExplanation / Answer
5a. Detection of Zn
Reagent : K4Fe(CN)6
Observation : gray-blue color precipitate formed
Equation,
3Zn2+ + 2K4Fe(CN)6 --> Zn3K2[Fe(CN)6]2 + 6K+
5b. Detection of Ni
Reagent : DMG
Observation : strawberry red precipitate
Equation,
Ni2+ + 2C4H7N2O2- --> Ni(C4H7N2O2)2
5c. Detection of Mg
Reagent : Magnesium reagent (4-(p-nitrophenylazo)resorcinol)
Observation : Blue-lake formation
Equation,
Mg2+ + 2OH- + Mg-reagent ---> Mg(OH)2 absorbed on Mg-reagent
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