Dam. 658-Separation
of A1 fnm Ni
To show: Separation of Group I11 (e.g., Al+++) from Group IV (e.g., Ni++) in routine qualitative analysis. Materials: C-3, AlClr-aq, NiCbaq, NH,OH, NaB-aq, filter paper, funnel. Procedure: Project C-3 with cells half-filled with water plus a few drops of Ni++ and Al+++ solution. (a) To cell 2 add NH,OH. (b) To cell 3 add NH,OH; filter; add NaS-aq to the filtrate. Observations: (a) A1(OH)3 precipitates out, but Ni++ stays in solution as the complex Ni(NH&+%. (b) Al(0H)a is retained on the filter paper, but NiS (grey) precipitates.
Dam. 659-Separation
of Ni from Ba
To show: The separation of Group IV (e.g., Ni++) from Group V (e.g., Ba++) in routine qualitative analysis. Materials: C-3, NiChaq, NazS-aq, BaC12, (NH4)+2O3, filter paper, funnel. Procedure: Project C-3 with cells three-quarters full of water plus a dropperful of NiClraq and BaClz-aq. (a) To cell 2 add NaS, filter. (b) To cell 3 add NaS, filter, add (NH&C03 to the filtrate. Observations: (a) Grey NiS precipitates and is retained on the filter paper; Ba++ remains in the filtrate; (b) BaC03 is precipitated slowly in the filtrate.
Dam. 660-Confirming Nickel
To shorn: The confirmatory test for Ni++ in routine qualitative analysis. Materials:
C-3, NiClz-aq, dimethyl glyoxime solution.
Procedure: project C-3 cells three-quarters full of water containing progressively diluted NiC12 solutions (e.g., 1 M, 0.01 M, 0.0001 M, etc.). Add a half dropperful of dimethyl glyoxime to each. Observations: A scarlet precipitate (a pink suspension in very dilute solutions) forms, formula X-Ni-X where X is
This is a test for traces of Ni++, and can be used colorimetrically for a rough quantitative estimate.
A538
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Journal o f Chemical Education
