Wet Test Analysis for Acid Radicals: Examination of Barium Chloride Group | Chemistry by Burhan Ishaque

 

(Group II: SO₄^-2, C₂O₄^-2, PO₄^-3, C₄H₃O₆^-3, BO₃^-3).

Add BaCl₂ solution in slight excess to ordinary solution (free from heavy metal). A ppt. is formed, filter.

Sr. no.	Observations	Inferences & Confirmations
1.	Ppt. is insoluble in all acids even in conc. HNO3.	Sulphate (SO4-2). Confirmations: 1.       O.S + (CH3COOH)2 Pb → white ppt. soluble in excess of CH3COONH4 solution. 2.       Heat the white ppt. obtained in the above-mentioned step 1, with equal quantity of Na2CO3 in a charcoal cavity. Take out the residue and dissolve it in water. Add NH4OH and sodium nitroprusside → a deep violet color.
2.	Ppt. is insoluble in hot dilute CH3COOH but soluble in hot dilute HNO3.	Oxalate (C2O4-2). Confirmation: 1.       Aq. Solution + dilute H2SO4 + KMnO4 → KMnO4 color will be discharged on warming. 2.       Aq. Solution + CaCl2 → white ppt. insoluble in acetic acid but soluble in HCl on heating. 3.       Salt → mass turns black 4.       O.S + AgNO3 → white ppt. 5.       O.S + resorcinol crystals + conc. H2SO4 → blue ring at the zone of contact.
3.	Ppt. is soluble in hot dil. CH3COOH.	a)       Phosphate (PO4-3). Confirmation: 1.       O.S + FeCl3 → yellow ppt. 2.       O.S (free from Cl-) + AgNO3 → yellow ppt. soluble in HNO3. 3.       O.S + conc. HNO3 + ammonium molybdate → yellow ppt. or color. 4.       Mixture + conc. HNO3 + ammonium molybdate → yellow ppt. or color. 5.       Heat the solid salt in charcoal cavity, add 2 drops of cobalt nitrate solution and heat again → blue mass. 6.       Aq. Solution + NH4Cl + NH4OH + MgSO4 → white ppt. of Mg3(PO4)2.   b)      Tartrate (C4H3O6-3). Confirmation: 1.       O.S + CaCl2 solution → white crystalline ppt. 2.       Na2CO3 extract + CuSo4 + NaOH → bright blue solution.   c)       Borate (BO3-3‑). Confirmation: 1.       O.S + conc. H2SO4 + C2H5OH → green Flame (on heating & ignite).