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2. WE + acidified K2Cr2O7 2 = sol 3 turns green 3. WE + acidified KMnO4 = pink colour of KMnO4 is discharged 4. Sulphide: Colourless gas with a smell of rotten eggs (H2S); turns lead acetate paper black 1. Sodium nitroprusside test: WE + sodium nitroprusside 4 = purple / violet colour 2. Lead acetate test: WE + lead acetate 5 (aq) = black ppt 5. Nitrite: Pungent light brown gas 1. Starch-iodide test: WE + dil H2SO4 (or dil acetic acid); boil, then add solid KI + fresh starch sol = deep blue colouration Group II (conc H2SO4 group) – Cl(chloride), Br- (bromide), I- (iodide), NO3- (nitrate), CH3COO- (acetate), C2O42(oxalate): Salt + conc H2SO4 1. No reaction: Group II anion not present. Continue to group III. 2. Chloride: Colourless white pungent fumes (HCl); intensify when glass rod dipped in NH4OH is brought near mouth of test tube 1. Silver nitrate test: WE + AgNO3 = white ppt soluble in NH4OH 2. Chromyl chloride test: Salt + solid K2Cr2O7 + 2-3 drops conc H2SO4 = orange / red fumes of chromyl chloride 6 1. Vapours + NaOH (aq) = yellow solution 2. Yellow solution + acetic acid + lead acetate sol = yellow ppt 2 3 4 5 6 Potassium dichromate Solution Na2[Fe(CN)5NO] Pb(CH3COO)2 CrO2Cl2
Test mentioned next to group is the preliminary test; the ones mentioned under an anion are confirmatory tests for it. Group I (dilute H2SO4 group) – CO32(carbonate), SO32- (sulphite), S2(sulphide), NO2- (nitrite): Salt + dil H2SO4 1. No reaction: Group I anion not present. Continue to group II. 2. Carbonate: Colourless and odourless gas (CO2) 1. WE 1 + MgSO4 = white ppt 3. Sulphite: Colourless gas with pungent smell 1. WE + BaCl2 (aq) = white ppt soluble in dil HCl 1 Water extract: Pinch of salt + water
3. Bromide: Reddish brown vapour 1. Silver nitrate test: WE + AgNO3 (aq) = yellow ppt partially soluble in NH4OH 2. Organic layer test: WE + CCl4 + 1 drop conc HNO3 = Upper layer aqueous; lower layer organic of orange / brown colour (bromine is soluble in Group III anions (special group) – non-polar solvent) SO42- (sulphate), PO43- (phosphate): No group reagent 4. Iodide: Violet vapours 1. Silver nitrate test: WE + 1. Sulphate: AgNO3 (aq) = yellow ppt 1. Barium chloride test: WE + insoluble in NH4OH BaCl2 (aq) = white ppt 2. Organic layer test: WE + CCl4 insoluble in conc HCl + 1 drop conc HNO3 = Upper 2. Lead acetate test: WE + lead layer aqueous; lower layer acetate (aq) + acetic acid = organic of violet colour (iodine white ppt soluble in is soluble in non-polar solvent) CH3COONH (ammonium acetate) 5. Nitrate: Brown fumes with pungent smell, which intensify on 2. Phosphate: adding paper pellets (may need 1. Ammonium molybdate test: heating) WE + dil HNO3 + ammonium 1. Brown ring test: WE + freshly molybdate 7 + boil = prepared FeSO4 sol + 1 drop crystalline canary yellow ppt conc HNO3 added along side of test tube = brown ring formed at junction of sol and acid 6. Acetate: Pungent vapour with vinegar-like smell 1. Ester test: Salt + conc H2SO4 + ethanol = fruity smell of ester 2. Ferric chloride test: WE + FeCl3 (aq) = brick red colour 1. Add dil HCl = red colour disappears 2. Add water and boil = reddish brown ppt
= white ppt; ppt dissolves when dil HNO3 is added and warmed 2. Potassium permanganate test: Salt + dil H2SO4 + heat; then add 2-3 drops KMnO4 sol = pink colour of KMnO4 is discharged
7. Oxalate: Colourless gas with effervescence (CO + CO2) 1. Calcium chloride test: WE + acetic acid + CaCl2 (aq) + boil 7 (NH4)2MoO4 www.ankurb.info
Group reagent is mentioned next to group cations. Test mentioned next to cation is the preliminary; ones under it are confirmatory tests for it. When sulphate is detected, Ba2+, Ca2+, Pb2+, and Sr2+ are not present as sulphates of these...