Qualitatve Inorgnic Analysis of cation and Anion.pptx

Qualitative analysis

1. Qualitative Analysis of Inorganic salts : Basic radicals (Cations) Cation is known as Basic radical. Pb 2+ , Hg 2+ , Cd 2+ , Cu 2+ , Al 3+ , Fe 3+ . NH 4+ etc. Basic radicals are grouped in 7 groups on the basis of their salt precipitate. Zero group : Ammonium ion – No group reagent 1 st group : Precipitate as Chloride by Dil HCl :- Pb 2+ 2 nd group : Precipitate as sulphide by H 2 S in presence of Dil HCl - Pb 2+ , Cu 2+ , (Black ppt.) As 3+ , (Yellow ppt.)

2. Qualitative Analysis of Inorganic salts 3 rd group : precipitated as hydroxide by NH 4 OH in the presence of NH 4 Cl. - Al 3+ (gelatinous white) Fe 3+ (reddish brown), Cr 3+ (green). 4 th group : precipitate as sulphide by H 2 S in the above ammonical solution. Mn 2+ ( Buff / skin colour ), Zn 2+ (greyish white ), Ni 2+ & Co 2+ (black). 5 th group: precipitate as carbonate with (NH 4 ) 2 CO 3 in above solution. - Ca 2+ , Ba 2+ , Sr 2+ (white ppt. in each case). 6 th group: 6 th group test for Mg 2+

3. Qualitative Analysis of Inorganic salts : Acidic radicals (Anions) Anion is Acidic radical – CO 3 2- , NO 2 - , NO 3 - , Cl - , Br - , I - , SO 4 2- etc. Acidic radicals are classified in three groups on the basis of reagent with which they reacts. 1 st group :- Reacts with dilute H 2 SO 4 : Carbonate (CO 3 2- ), bicarbonate (HCO 3 -1 ), sulphide (S 2- ), sulphite (SO 3 2- ), nitrite (NO 2 - ) 2 nd group :- Reacts with Conc. H 2 SO 4 ; Chloride (Cl - ), Bromide (Br - ), Iodide (I - ), Nitrate (NO 3 - ), Acetate (CH 3 COO - ) 3 rd group: Sulphate (SO 4 2- ), Phosphate (PO 4 3- )

4. Qualitative estimation of salts involves three steps Preliminary Test ; Test or taking inferences on the basis of physical properties of the salt i.e. colour, smell, Flame test etc. Confirmatory Test for Acidic Radicals: Test which confirms the presence of a particular Anion Confirmatory test for Basic radicals : Test which confirms the presence of a particular Anion Qualitative Estimation of Anions (Acidic radicals) and Cations (Basic Radicals)

5. Preliminary Test 1 Colour Observation: observe the colour of the salt and match with record 2 Smell : Take a pinch of Salt on palm and rub it by finger them smell your palm. Colour Salt Blue Cu 2+ Light Green , Yellow, Brown Fe 2+ , Fe 3+ Blue, Red, Violet, Pink Co 2+ Light Pink Mn 2+ Bright Green Ni 2+ Smell Salt Vinegar CH 3 COO - Rotten Egg S 2- Ammonia smell NH 4 +

6. Preliminary Test 3 4 Flame Test: Make a paste of salt with conc. HCl and then burn in blue flame with the help of Platinum wire Colour Salt Apple green Ba 2+ Crimson Red Sr 2+ Brick Red Ca 2+ Bluish Green Cu 2+ Dry heating Test: Take about 0.1g of dry salt in clean and dry test tube. Heat the above solution and observe the solution when it is hot & also when it becomes cold. Colour when cold Colour when hot Inference Blue White Cu 2+ Green Dirty White Fe 2+ White Yellow Zn 2+ Pink Blue Co 2+

7. Preliminary Test 5 Borax Bead test : Make a loop of platinum wire and heat it in flame till it red hot. Dip the loop in borax powder and heat again until borax forms a colourless bead. Dip the bead in dry salt and again hold it in flame. Observe the colour of the bead in luminous flame and No-luminous flame when hot and when cold. Na 2 B 4 O 7 .10H 2 O (Borax) → Na 2 B 4 O 7 → 2 NaBO 2 (Sodium metaborate) + B 2 O 3 (Boric anhydride) CuSO 4 + B 2 O 3 Cu(BO 2 ) 2 (cupric metaborate) Blue-green + SO 3 Two reactions may take place in the reducing flame : ( i ) The blue Cu(BO2)2 is reduced to colourless cuprous metaborate as follow : CuSO 4 + B 2 O 3 2CuBO 2 + 2Na 2 B 4 O 7 + CO  

8. Preliminary Test 5 Heating in oxidizing (Non-luminous) flame Heating in oxidizing (Non-luminous) flame Inference Colour of the salt bead Colour of the salt bead In cold In hot In cold In hot Blue Green Red opaque Colourless Cu 2+ Reddish brown Violet Grey Grey Ni 2+ Light violet Light violet Colourless Colourless Mn 2+ Yellow Yellowish brown Green Green Fe 3+