CHEMISTRY QUALITATIVE INORGANIC ANALYSIS
S.N. Experiment Preliminary Tests • 1.
Colour :
* Colourless(white) * Blue or bluish green * Light green * Dark green * Pink violet * Light pink Odour: A pinch of the salt is * No characteristic smell taken and rubbed with a drop * Ammoniacal smell of water. * Vinegar smell Solubility: *Soluble in water *Soluble in dil.HCl *Colourless odourless gas Dry heating test:A small amount of salt is heated in a turns lime water milky. dry test tube. *Pungent smelling gas, white fumes with NH NH4 OH *Vinegar smell *White sublimate formed on the walls of test tube. *Yellow when hot and white when cold. Flame test:A little of the salt is *No characteristic colour made into paste with conc.HCl. *Golden yellow A platinum wire is dipped in *Lilac the paste and showed on the *Apple green flame. *Crimson red *Brick red *Bright bluish green
2
3. 4.
5.
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1.
Observation
Inference +
+
+
Absence of Cu ,Ni ,Co etc. 2+ 2+ Presence of Cu or Ni . 2+ Presence of Fe . 3+ Presence of Cr . 2+ Presence of Co . 2+ Presence of Mn . + Absence of NH4 orCH3COO + NH4 may be present. CH3COO may be present. + NH4 may be present. 2+ Pb may be absent. CO3 may be present. -
Cl may be present. -
CH3COO may be present. + NH4 may be present. 2+
Zn may be present. +
+
+
Absence of Ba , Sr , Ca etc + May be presence of Na + May be presence of K 2+ May be presence of Ba 2+ May be presence of Sr 2+ May be presence of Ca 2+ May be presence of Cu
Systematic analysis of acid radicals(anions) Dil.H2SO4 test: a)To a little of the salt 1-2 ml. of dil.H2SO4 is added. b)A Little of the salt is rubbed with dil.H2SO4 in a watch glass
*Brisk effervescence with the liberation of colourless odourless gas. *Vinegar smell
1
Presence CO3
2-
-
Presence of CH3COO (acetate)
2.
Conc. H2SO4 test: A little of the salt is heated with 2ml conc. H2SO4.
3.
A little of the salt is acidified with dil.HCl and BaCl2 solution is added. A little of the salt is acidified with dil.HNO3 and excess of ammonium molybdate solution is added.
4.
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1.
2.
3.
4.
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*Colourless gas with pungent smell and gives dense white fumes when a glass rod dipped in NH4OH is shown at the mouth of the test tube. * Light brown fumes with pungent smell becomes dark brown on heating with copper turnings(paper ball) *Reddish brown fumes with pungent smell. * Deep violet vapours * Colourless gas with vinegar smell White precipitate
Presence of Cl
Presence of SO4
-
Yellow precipitate
Presence of PO4
-
White precipitate
Presence of CO3 is confirmed.
Red colour
Presence of CH3COO is confirmed.
White precipitate soluble in NH4OH
Presence of Cl is confirmed.
Orange red precipitate
Presence of Cl is confirmed.
*Pale yellow precipitate sparingly soluble in NH4OH *Yellow precipitate insoluble in NH4OH
Presence of Br is confirmed.
Presence of NO3
-
-
Presence of Br -
Presence of I Presence of CH3COO
Confirmatory tests for acid radicals -
Carbonate(CO3 ): To a little of the salt solution, few drops BaCl2 solution is added. Acetate(CH3COO ): To a little of the salt solution neutral ferric chloride solution is added. Chloride(Cl ) a)To a little of the salt solution dil.HNO3 and AgNO3 solutions are added. b)Chromyl chloride test: A little of the salt is heated with potassium dichromate and conc. H2SO4. - Bromide and iodide(Br ,I ): To a little of the salt solution dil.HNO3 and AgNO3 solutions are added.
2
2-
-
-
-
-
-
Presence of I is confirmed.
-
5.
Nitrate(NO3 ): Brown ring test:A small quantity of freshly prepared FeSO4 solution is added to a little of the salt solution and then conc. H2SO4 is added along the sides of the test tube. 2Sulphate(SO4 ): To a little of the salt solution acetic acid and lead acetate are added. Phosphate(PO4 ): To a little of the salt solution few drops of magnesia mixture is added.
6.
7.
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2. 3.
4.
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7.
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A brown ring is formed at the junction of the layers.
Presence of NO3 is confirmed.
White precipitate soluble in excess of ammonium acetate solution. White crystalline precipitate
Presence of SO4 is confirmed.
Smell of ammonia and gives dense white fumes when a glass rod dipped in conc.HCl is shown at the mouth of the test tube. White precipitate.
Presence of NH4 (0 group)
2-
-
Presence of PO4 is confirmed.
Systematic analysis of basic radicals (Prepare a solution of the salt in water) A little of the salt is heated with NaOH solution.
To a little of the salt solution , dil.HCl is added. If no precipitate, H2S gas is passed through the above solution. Solid NH4Cl and excess of NH4OH is added to the salt solution. If no precipitate, H2S gas is passed through the above solution. Solid NH4Cl , excess of NH4OH and (NH4 )2CO3 are added to the salt solution. To a little of the salt solution, solid NH4Cl ,excess of NH4OH, and disodium hydrogen phosphate solutions are added. The inner side of the test tube is scratched with a glass rod.
Yellow or black precipitate.
White gelatinous precipitate or reddish brown precipitate. Dirty white, pink or black precipitate. White precipitate.
White precipitate.
3
+
Presence of group I 2+ cations.(Pb ) Presence of group II cations. 2+ 2+ (Cu - black, Cd -yellow) Presence of group III cations. 3+ (Al -white gelatinous, 3+ Fe -reddish brown) Presence of group IV cations. 2+ 2+ 2+ (Zn -white,Mn -pink,Co 2+ or Ni -black) Presence of group V cations. 2+ 2+ 2+ (Ba , Sr or Ca ) Presence of group VI cations. 2+ (Mg )
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2.
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4.
5.
Confirmatory tests for basic radicals Group 0 (Ammonium ion): To a little of the salt solution NaOH is added and then Nessler’s reagent. + Group I cation (Pb ) a)To a little of the salt solution, few drops of potassium chromate solution are added. b)To a little of the salt solution, few drops of potassium iodide solution are added. + + Group II cations (Cd ,Cu ) Group II precipitate is boiled with dil.HNO3 and NH4OH is added in drops and then in excess. +
+
Brown precipitate.
Presence of NH4 is confirmed.
Yellow precipitate.
Presence of Pb is confirmed.
Golden yellow precipitate .
Presence of Pb is confirmed.
*White precipitate soluble in excess NH4OH. *Pale blue precipitate changes to deep blue solution.
Presence of Cd is confirmed. 2+ Presence of Cu is confirmed
Blue floating precipitate.
Presencs of Al is confirmed.
Blue ashes.
Presencs of Al is confirmed.
Blood red colour
Presence of Fe is confirmed.
White precipitate
Presence of Zn is confirmed.
Green ashes.
Presence of Zn is confirmed.
2+
+
2+
+
Group III cations (Al ,Fe ) 3+ Test for Al : a) Lake test: Group III precipitate is dissolved in dil.HCl and two drops of blue litmus solution is added followed by NH4OH dropwise b) Ash test:A little of the salt is dissolved in few drops of conc. HNO3 and boiled with cobalt nitrate solution. A filter paper soaked in this solution and burnt to ashes. + Test for Fe : Potassium thiocyanate is added to the salt solution. + + Group IV cations(Zn ,Co , 2+ 2+ Ni , Mn ) 2+ Test for Zn : a)To a little of the salt solution few drops of potassium ferrocyanide solution are added. b) Perform ash test.
4
3+
3+
3+
2+
2+
+
6.
7.
Test for Co : NaOH is added to a little of the salt solution in drops to excess and warmed. 2+ Test for Ni : To a little of the salt solution, NH4OH is added in excess followed by dimethyl glyoxime reagent. + Test for Mn : Salt solution is boiled with few drops of conc.HNO3 and a pinch of lead peroxide.Boil, cool and allow to settle. 2+ 2+ Group V cations (Ba ,Sr , 2+ Ca ) 2+ Test for Ba : To a little of the salt solution acetic acid and potassium chromate solutions are added. 2+ Test for Sr : To a little of the salt solution acetic acid and ammonium sulphate solutions are added 2+ Test for Ca : To a little of the salt solution ammonium chloride, ammonium hydroxide and ammonium oxalate solutions are added.
2+
A blue precipitate formed in the cold changed to pink on warming.
Presence of Co is confirmed.
A red rose precipitate.
Presence of Ni is confirmed.
A pink coloured solution.
Presence of Mn is confirmed.
Yellow precipitate.
Presence of Ba is confirmed.
White precipitate.
Presence of Sr is confirmed.
White crystalline precipitate
Presence of Ca is confirmed.
2+
2+
2+
2+
2+
+
Group VI cations (Mg ) a) To the salt solution NH4Cl, NH4OH in excess and ammonium phosphate solutions are added. Rub the sides of the test tube with a glass rod. b) Perform ash test.
2+
A white precipitate.
Presence of Mg is confirmed.
Pink ashes.
Presence of Mg is confirmed.
2+
GEETHA.K OOEHS, SHJ(BOYS)
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