Qualitative Analysis of Group III Cations PDF

ANACHEM - LEC Reviewer Role of 𝑁𝐻4𝐶𝑙 Controls 𝑂𝐻 − Qualitative Analysis of Group III Cations...

ANACHEM - LEC Reviewer Role of 𝑁𝐻4𝐶𝑙 Controls 𝑂𝐻 − Qualitative Analysis of Group III Cations 𝑁𝐻4𝐶𝑙 concentration (Iron-Aluminum Group) thru common ion effect, preventing Group III-A (Ammonium Hydroxide Group): precipitation of GIIIB and 3+ 3+ 𝐹𝑒 , 𝐴𝑙 , 𝐶𝑟 3+ - precipitates as hydroxides 𝑀𝑔(𝑂𝐻)2 - Group reagents: 𝑁𝐻4𝐶𝑙 + 𝑁𝐻4𝑂𝐻 Boiling after Heat Coagulates Group III-B (Zinc subgroup ; Ammonium 𝑁𝐻4𝐶𝑙 ppt, breaks 𝐶𝑟 amine Sulfide Group): - ppt as sulfides complex, and 2+ 2+ 𝑀𝑛 , 𝑍𝑛 , 𝐶𝑜 , 𝑁𝑖 2+ 2+ prevents 2+ 𝑀𝑛 - Group reagents: oxidation 𝑁𝐻4𝐶𝑙 + 𝑁𝐻4𝑂𝐻 + 𝐻2𝑆 Separation of𝑁𝑎𝑂𝐻 + 3+ 𝐴𝑙 forms 3+ 3+ 𝐹𝑒 , 𝐴𝑙 , 𝐶𝑟 (for the 3+ 𝐻2𝑂2 soluble Group III-A Cations 3+ 3+ (𝐹𝑒 , 𝐴𝑙 , 𝐶𝑟 ): 3+ oxidation of aluminate − 𝐶𝑟𝑂2 which (𝐴𝑙𝑂2 ); 𝐶𝑟 − 3+ Ammonium Hydroxide Group is unstable forms chromite chromate ( Step Reagents & Process & 2− Conditions Explanation ↳ 𝐶𝑟04 , yellow) Boil the Heat Removes filtrate from 𝐻2𝑆 to GII prevent the 2+ 2+ 2+ 2+ precipitation Group III-B Cations (𝑀𝑛 , 𝑍𝑛 , 𝐶𝑜 , 𝑁𝑖 ): of GIIIB with Zinc subgroup; Ammonium Sulfide Group IIIA Step Reagents & Process & Oxidation of Conc. 𝐻𝑁𝑂3 𝐻2𝑆 reduces Conditions Explanation 2+ 3+ 3+ 2+ 𝐹𝑒 to 𝐹𝑒 𝐹𝑒 to 𝐹𝑒 ; 4 oxidation Precipitation 𝑁𝐻𝐶𝑙 + MnS (buff ensures 𝐹𝑒 3+ as Sulfides 𝑁𝐻4𝑂𝐻 + ppt) precipitation 𝐻2𝑆 ZnS (white as 𝐹𝑒(𝑂𝐻)3 ppt) which has a CoS (black lower Ksp ppt) than 𝐹𝑒(𝑂𝐻)2 NiS (black ppt) Precipitation 𝑁𝐻4𝐶𝑙 + 𝐹𝑒(𝑂𝐻)3: of Hydroxides 𝑁𝐻4𝑂𝐻 reddish Dissolving Dil. 𝐻𝐶𝑙 𝑍𝑛 2+ and brown 2+ 𝐴𝑙(𝑂𝐻)3: 𝑍𝑛 and 𝑀𝑛 2+ white 2+ 𝑀𝑛 dissolve, gelatinous leaving NiS 𝐶𝑟(𝑂𝐻)3: and CoS greyish-green Oxidation of 𝑁𝑎𝑂𝐻 + 𝐵𝑟2 𝑀𝑛(𝑂𝐻)2 water oxidized to  𝑀𝑛 2+ 𝑀𝑛𝑂2 (black 𝑍𝑛 2+ 𝐻2𝑆 Test 𝐻2𝑆 White ppt) ppt of ZnS Separation of Ferrous and Manganous Ions 2+ Ferrocya Acetic Acid Sky 𝑍𝑛 nide Test + Potassium blue ppt Step Reagents & Process & Ferrocyanid Conditions Explanation e Dissolution 𝐻𝑁𝑂3 + 𝐹𝑒(𝑂𝐻)3 2+ Ferricyani 𝑁𝐻4𝑐𝑙 + Red ppt of 𝐻2𝑂2 and 𝐶𝑜 de Test 𝑁𝐻4𝑂𝐻 + Precipitates 𝑀𝑛(𝑂𝐻)2 Potassium will dissolve Ferricyanide Test Ferric Test 𝑁𝐻4𝑆𝐶𝑁 3+ 𝐹𝑒 gives blood red 𝐶𝑜 2+ Vogel 𝐻2𝑆𝑂4 + Blue solution Test 𝑆𝑛𝐶𝐿2 + color in Ether + ether Manganese 𝑃𝑏3𝑂4 + 2+ 𝑁𝐻4𝑆𝐶𝑁 layer 𝑀𝑛 gives Test 𝐻2𝑂2 − pink 𝑀𝑛𝑂4 2+ Dimethyl DMG Red ppt 𝑁𝑖 Glyoxime Test Confirmatory Tests 2+ 𝑁𝑖 KCN Test 𝐾𝐶𝑁 + Black Cations Test Reagent(s) Result 𝑁𝑎𝑂𝐻 + 𝐵𝑟2 𝑁𝑖𝑂2 3+ 𝑁𝐻4𝑆𝐶𝑁 𝑁𝐻4𝑆𝐶𝑁 Blood Water ppt 𝐹𝑒 Test red solution 𝐹𝑒 3+ Ferrocya Potassium Prussia nide Test Ferrocyanid n blue e ppt 𝑀𝑛 2+ Red Lead 𝑃𝑏3𝑂4 + Pink Test 𝐻2𝑂2 solution 𝐶𝑟 3+ Pb Pb Acetate Yellow Acetate ppt of Test 𝑃𝑏𝐶𝑟𝑂4 𝐶𝑟 3+ Perchrom 𝐻2𝑆𝑂4 + Blue ic Acid Ether + color in Test 𝐻2𝑂2 ether layer 𝐴𝑙 3+ 𝑁𝐻4𝐶𝑙 𝑁𝐻4𝐶𝑙 White Test gelatino us layer