EXPERIMENT No:-5
AIM: To identify the acid and basic radicals present in the given sample.
(A)PHYSICAL CHARACTERISTICS:
(i) Colour-White
(ii) Odour: Odourless
(iii) State: crystalline
(iv) Solubility: soluble in water
(B) DRY TESTS FOR ACID RADICALS:-
S.No Experiment Observation Inference
i Dilute sulphuric acid test – To a pinch of salt taken No brisk effervescence CO32- absent
in a dry test tube, 1-2 ml of dil. H2SO4 was added. No gas with smell of SO32- absent
burning sulphur
No gas with rotten egg S 2- absent
smell
No reddish brown gas NO2-absent
ii Oxalic acid test- To a pinch of the salt taken on a No smell of vinegar. CH3COO- absent
watch glass, oxalic acid crystals and few drops of
water were added to make a paste.
iii MnO2 test- To a pinch of the salt taken in a dry test No greenish yellow gas Cl-absent
tube equal amount of MnO2,1-2ml conc. H2SO4 was with pungent smell.
added and heated. No reddish brown Br-absent
pungent vapours
No deep violet pungent I - absent
vapours
iv Copper turning test- To a pinch of salt taken in a No dark brown fumes NO3-absent
dry test tube, 1-2 ml conc. H2SO4 was added and evolved.
heated along with few copper turnings.
(C) WET TEST FOR CONFIRMATION OF ACID RADICAL:-
(i) Preparation of original solution- A little amount of salt was taken in a clean dry test tube to which 5 ml distilled
water was added. The test tube was shaken till the salt dissolved and a clear solution was obtained. This solution is
labeled as original solution (OS)
2-
(ii) Test for SO4
Experiment Observation Inference
(i) BaCl2 test: To a part of the OS, 1-2 ml BaCl2 Thick white precipitation Presence of
solution was added. insoluble in mineral acids sulphate radical
confirmed
(ii) Lead acetate test: To the OS few drops of acetic acid Thick white precipitation Presence of
and lead acetate solution were added. insoluble in mineral acids sulphate radical
confirmed
CHEMICAL REACTIONS INVOLVED:-
2- -
(i) SO4 (aq) + BaCl2 (aq) BaSO4(white ppt, insoluble in mineral acids) + 2Cl
2- -
(ii) SO4 (aq)+ Pb(CH3COO)2 (aq)PbSO4(white ppt,insoluble in mineral acids)+2CH3COO
(D) DRY TESTS FOR DETECTION OF BASIC RADICALS:-
S.No Experiment Observation Inference
(i) NaOH bead test-To a pinch of salt taken in a dry test No ammoniacal smell Ammonium radical
tube, 1or2 pellets of NaOH was added and heated absent
(ii) Flame test-A paste of salt with conc HCl was placed No characteristic flame Pb2+ , Zn2+, ,Ca2+ ,
on the loop of a clean platinum wire and introduced to colouration 2+ 2+
Sr , Ba radicals
the non-luminous flame.
are absent
(E) GROUP ANALYSIS:
To the aqueous solution of the sample 1 ml of dil HCl is added.
No H2S gas is passed through the above acidified solution.
white
ppt. To the aqueous solution of the sample, solid NH4Cl followed by NH4OH
Gr. 1 No ppt. solution is added till excess.
basic Gr. 2
White ppt.
basic
radical Gr. 3 basic radical
radical is
is present.
absent
absent 3+
May be Al .
(F)CONFIRMATORY TEST FOR BASIC RADICAL:-
EXPERIMEN OBSERVATION INFERENCE
T
Lake test: To the OS, A blue ppt suspended in a Presence of aluminium
a few drops of blue colourless medium 3+
radical(Al ) confirmed
litmus solution and
excess NH4OH
solution are added
CHEMICAL EQUATIONS INVOLVED:
(i) Al2(SO4)3 + 6NH4OH 3(NH4)2SO4 + 2Al(OH)3 (White ppt)
(ii) Lake test: Al2(SO4)3 + 6NH4OH 3(NH4)2SO4 + 2Al(OH)3 (White ppt)
( blue colour of litmus adsorbs on this ppt)
(G) RESULT
Acid radical : Sulphate (SO42-)
Basic radical : Aluminium(Al3+)
Salt :- Aluminium sulphate [ Al2(SO4)3 ]
