Identify two acid and two basic radicals in a given inorganic mixture and report
Answers
Acid radical : NO3–
Basic radical : Ba2+.
1. Physical examination:
(a) Noted the colour of the given salt.
(b) Noted the smell of the salt.
White
No specific odour
Cu2+, Mn2+, Co2+, Ni2+, Fe3+ absent.
NH4+, S2- and CH3COO– may be absent.
2. Dry heating test
Heated a pinch of the salt in a dry test tube and noted the following observations :
(a) Gas evolved
(b) Sublimation
(c) Decrepitation
(d) Colour of the residue
A reddish brown gas evolved which turned FeSO4 solution black.
No sublimate formed.
No crackling sound observed.
White
N03- may be present.
Ammonium halides, aluminium chloride, iodide may be absent.
Lead nitrate, barium
nitrate, may be absent.
Ba2+, Sr2+, Ca2+, Al3+, Mg2+, etc., may be
present.
3. Charcoal cavity test
Mixed a pinch of the salt with double the quantity of Na2CO3 and heated the mixture on a charcoal cavity in the reducing flame.
White residue.
Ba2+, Sr2+, Ca2+, Al3+, Mg2+,
etc., may be present.
4. Cobalt nitrate test
To the above white residue added a drop of cobalt nitrate solution. Heated it in oxidising flame.
No characteristic colour.
Al3+, Zn2+„Mg2+, PO43-, may be absent.
5. Flame test
Prepared a paste of the salt
with cone. HCl and performed flame test.
Persistent grassy green flame
on prolonged heating.
Ba2+ present.
6. Borax bead test
Did not perform this test since the given salt was white.
– Cu2+, Mn2+, Co2+, Ni2+, Fe3+ may be absent.
7. Dil. sulphuric acid test
Treated a pinch of the salt with dil. H2SO4 and warmed.
No gas evolved.
CO32-, S2-, SO32-, NO2– may be absent.
8. KMnO4 test
To a pinch of the salt added dil. H2SO4 and a drop of KMnO4 solution.
Pink colour of KMnO4 was not
discharged.
Cl–, Br–, I–, C2O42- and Fe2+ may be absent.
9. Cone, sulphuric acid test
Heated a pinch of the salt with cone, sulphuric acid and added to it a paper pellet.
A reddish brown gas evolved which turned FeSO4 solution black. NO3– may be present.
10. Confirmatory test for ni-trate
(a) Copper chips test. Heated a pinch of the salt with cone, sulphuric acid and a few copper chips.
(b) Ring test. To 2-3 ml of the salt solution, added freshly pre-pared FeSO4 solution. Then added cone, sulphuric acid along the sides of the test tube.
Reddish brown gas evolved.
A dark brown ring formed at the junction of the two liquids.
NO3– confirmed.
NO3– confirmed.
11. Heated a pinch of salt with cone. NaOH solution No ammonia gas evolved. NH4+ absent.
12. Preparation of Original Solution (O.S.)
Shook a pinch of the salt with water.
Solution obtained
Labelled it as Original Solution (O.S.)
13. To a part of the O.S. added 1-2 ml of dilute hydro-chloric acid. No ppt. formed. Group I absent. (Pb2+ absent)
14. Through a part of the above solution, passed H2S gas. No ppt. formed. Group II absent (Pb2+, Cu2+, As3+, absent)
15. To the remaining solution, added a pinch of solid ammonium chloride. Boiled the solution, cooled it and added excess of ammonium hydroxide solution. No ppt. formed.
Fe3+, Al3+ absent
16. Through a part of the above solution, passed H2S gas. No ppt. formed.
Group IV absent.
(Zn2+, Mn2+, Co2+ and Ni2+ absent)
17. To the remaining ammonical solution added ammonium carbonate solution. White ppt. formed. Group V present.
(Ca2+, Ba2+, Sr2+ may be present)
18. Confirmatory test for Ba2+ ion
Filtered the above white ppt. Dissolved the ppt. in hot dilute acetic acid.
(a) Pot. chromate test. To one part of the above solution, added a few drops of pot. chromate solution.
(b) Flame test. Performed flame test with the salt.
Yellow ppt.
Persistent grassy green flame on prolonged heating.
Ba2+ confirmed.
Ba2+ confir
Answer:
Explanation:identification of two acid and two basic radicals in NH4+ and Ba2+ and Cl-