Question

identify the cationic and a ionic radical in given unknoe salt a by performing dry anf wet test for cationic and anionic radical

Answer 1

this answer , i am only writing for a 12th practical. for full details please read qualitative analysis chapter.

[Dry test ]
There are many test available for dry test . But mostly, Borax bead test uses for analysis.
Borax bead test :-(Na2B4O7.10H2O) is heated on pt wire where it is dehydrated completely forming glass bead consisting of NaBO2 mad B2O3 . The bead is mixed than with salt to be tested and heated further.
Where colored metal metborates are formed.
eg., CuO + B2O3 --> Cu(BO2)2 (Green in hot And blue in cold)
Results of some Borax bead test with common metal is
Cu -- green (hot) ;blue(cold)
Fe -- yellowish-brown(hot);yellow(cold)
Cr --yellow(hot); green(cold)
Mn-- violet(hot); amethyst (cold)
Co-- blue(hot); blue (cold)
Ni-- violet (hot); reddish-brown(cold)


[wet test ] salt analysis (anions)
★test mentioned , the next to group is the primary test;the ones mentioned under an anions are confirmatory test.

group I(dilute H2SO4 group): -carbonate,sulphite, sulphide nitrite :salt + dil H2SO4
1. no reaction :-group I anion not present .continue to group II
2. carbonate :- colorless and odorless gas (CO2)
pinch of salt + water( water extract) + MGSO4 = white ppt
3.sulphite:- colorless gas with pungent smell.
pinch of salt + water + BaCl2 = white ppt ( soluble in dil HCl)
pinch of salt + acidicfied K2Cr2O7 = solution turn green color.
pinch of salt + water + acidified KMnO4 = discharged pink color of KMnO4
4. sulphide :-colorless gas with rotten egg smell.(H2S). also turn lead acetate paper in black.
pinch of salt + water + sodium nitroprusside =purple/violet color
5.nitrite:- light brown gas with pungent smell.
starch iodide test:- (pinch of salt + water dil H2SO4 )--boil , then add solid KI + fresh starch solution = deep blue coloration appear .

groupII(conc. H2SO4, group) :- Cl-, Br-, I-, NO3- , CH3COO-, C2O4 2-(oxalate) :salt + conc. H2SO4
1. no reaction :- group II anions not present. continue to groupIII
2. chloride(Cl-) :- colorless with pungent fumes(HCl) ; intensify when glass rod dipped in NH4OH is brought near mouth of test tube.
silver nitrate test:- pinch of salt + water + AgNO3 = white ppt soluble in NH4OH.
chromyl chloride test :- salt + solid K2Cr2O7 + (2-3 drop) of conc H2SO4 = orange /red fumes of chromyl chloride (CrO2Cl2)
vapors + NaOH(aq) = yellow solution.
yellow solution + acetic acid + lead acetate (sol) = yellow ppt

3. bromide(Br-) :- reddish brown vapor.
silver nitrate test :pinch of salt + water + AgNO3 = yellow ppt
organic layer test : pinch of salt + water + CCl4 + 1drop of conc. HNO3 = upper layer aqueous ;lower layer of oragnic is orange /brown color (Br is soluble in non-polar solvent)
4. iodide :- violet color,
silver nitrate test :pinch of salt + water + AgNO3 = yellow ppt.
organic layer test : pinch of salt + water + CCl4 + 1drop of conc. HNO3 = upper layer aqueous ;lower layer of oragnic is violet color( iodine is soluble in non-polar solvent).
5.nitrate- brown fumes with pungent smell, which is intensify on adding paper pallets(some times may need heating).
brown ring test : pinch of salt + water + freshy prepared FeSO4 + 1 drop conc. HNO3 added along side of tube test = brown ring formed at junction of solution and acid.
6. Acetate: Pungent vapour with vinegar-like smell.
Ester test: Salt + conc H2SO4 + ethanol = fruity smell of ester.
Ferric chloride test: pinch of salt + water + FeCl3 (aq) = brick red colour Add dil HCl = red colour disappears then Add water and boil =reddish brown ppt.

7.Oxalate: Colourless gas with effervescence (CO + CO2)Calcium chloride test:pinch of salt + water + acetic acid + CaCl2 (aq) + boil= white ppt; ppt dissolves when dil HNO3 is added and warmed.

Potassium permanganate : Salt + dil H2SO4 + heat;then add 2-3 drops KMnO4 sol = Discharged pink color of KMnO4

Group III anions (special group)– (sulphate),(phosphate): No group reagent.
1. Sulphate: Barium chloride test: pinch of salt + water + BaCl2 (aq) = white ppt
(insoluble in conc HCl).
Lead acetate test: pinch of salt + water + lead acetate (aq) + acetic acid = white ppt soluble in CH3COONH (ammonium acetate).
2. Phosphate: Ammonium molybdate test: Pinch of salt + water + dil HNO3 + ammonium molybdate+ boil = crystalline canary yellow ppt.

Answer 2

continue of abhi178 answer .......

salt analysis ( cation)
★ Group reagent is mentioned next to group cations.
★ Test mentioned next to cation isthe 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 radicals are insoluble.

★ When phosphate is detected, cations of group III and later are absent.


Group 0 – NH4+(ammonium): No group reagent.
Sodium hydroxide test: Salt + NaOH = pungent smelling gas;gives white fumes when a glass rod dipped in conc HCl is brought near mouth of test tube.
Nessler's reagent test: (salt + acid + water) original solution +NaOH + Nessler's reagent =
Brown / yellow ppt.

Group I – Pb2+ (lead):original solution ( salt + acid + water) + dil HCl = white ppt; add water, boil, and divide into three parts.
part 1:- Leave original solution undisturbed = white crystals formed on cooling.
Part 2:- Potassium iodide test: original solution + KI = yellow ppt.
part 3:- Potassium chromate test: original solution + K2CrO4 = yellow ppt.

Group II –group reagent is H2S in dilute acidic
medium.Cu2+ (copper):Original solution + dil HCl + H2S = black ppt
1.Throw off extra sol, retain ppt, and dissolve in a few drops of conc HNO3 = bluish green sol,ppt dissolves; divide into two
parts.
1.Part 1 + excess NH4OH = blue coloured solution.
2. Potassium ferrocyanide test: Part2 + acetic acid + K4[Fe(CN)6] = reddish brown /
chocolate coloured ppt (this test is difficult to get).

Group III – Fe2+, Fe3+ (iron), Al3+
(aluminium): original solution + solid NH4Cl + excess NH4OH
1. Fe2+ / Fe3+: ferrous salts are green in colour, ferric salts are brown in colour. If ferrous salt has been given, convert to ferric: original solution + conc HNO3 + heat = brown ppt;then do reaction with groupreagent now,
Brown ppt + HCl; then divide into two parts,
1. Potassium ferrocyanide test: Part 1 + K4[Fe(CN)6] = blue ppt /colour

2. Potassium thiocyanate test: Part 2 + KCNS = bloodred colour.

2. Al3+: Gelatinous white ppt Blue lake test: Retain ppt + dil HCl = clear solution.
1. Sol + blue litmus and NH4OH (drop-by-drop) = blue colour layer ('lake')floats over colourless solution.

continues with Group III – Co2+(cobalt), Ni2+(nickel),Mn2+ (manganese), Zn2+ (zinc):original solution + solid NH4Cl + excess NH4OH +pass H2S gas.

1. Co2+ / Ni2+: Black ppt; dissolve ppt in aqua regia and evaporate sol to dryness to get residue.

1. Co2+: Blue residue; turns pink / purple when dissolved in water; divide into two parts,

1. Part 1 + dil acetic acid + KNO2 + warm = yellow ppt
2. Part 2 + ether (1 mL) + solid NH4CNS = blue colour in ether

2. Ni2+: Yellow residue; turns green when dissolved in water; divide into two parts
1.dimethyl glyoxime (DMG) test: Part 1 +
excess NH4OH + DMG = bright red ppt

2. Part 2 + NaOH + bromine water + boil = black ppt.
2. Mn2+: Buff / skin color ppt; divide into two parts
1. Part 1 + dil HCl + boil off H2S + NaOH = white ppt; which turns black / brown on adding bromine water.

2. Lead dioxide test: Part 2 +PbO2 + conc HNO3 + boil = after cooling; pink coloration.

3. Zn2+: Greyish white ppt; divide into two parts,
1. Part 1 + excess NaOH =white ppt dissolves
2. Potassium ferrocyanide test: Part 2 + K4[Fe(CN)6] = white / bluish white ppt.

Group IV – Ba2+ (barium), Sr2+(strontium), Ca2+ (calcium): original solution + (NH4)2CO3 + NH4Cl + NH4OH = white ppt; add dil acetic acid, divide sol into three parts and test for following in order :

1. Ba2+: Part 1+ excess K2CrO4(aq) = yellow ppt

2. Sr2+: Part 2 + (NH4)2SO4(aq) =white ppt.
3. Ca2+: Part 3+(NH4)2C2O4(aq) + NH4OH (only if nothing appears at first) = white ppt.
4. Flame test: Take salt and make a paste by mixing with conc HCl. Take paste on tip of glass rod / platinum wire, and put in Bunsen
burner flame.
1. Ba2+: Green flame
2. Sr2+: Crimson red flame
3. Ca2+: Brick red flame

Group V – Mg2+ (magnesium) :- No group reagent .When reagent - NH3 : Mg(OH)2↓ (partial ppt ion)
when reagent - NaOH:Mg(OH)2↓ (white ppt)
When reagent -(phNHNH)2=0 : violet - red ppt with Mg(OH)2
When reagent - Titan yellow test : deep red ppt with Mg(OH)

remark :- insoluble in excess reagent but readily soluble in solution of ammonium salt.