Test for Acidic Radicals CO<sub>3</sub><sup>2-

Test for Acidic Radicals CO32-

S.No. Treatment Observation Inference
1 Salt + dil. H2SO4 Colourless, odourless gas with brisk effervescence Week acidic group present CO32- may be
2 Confirmatory test
Pass the above gas in lime water		 Lime water turns milky CO32- is confirmed
Pass the above gas in lime water for longer time Lime water again turn to colourless solution CO32- is confirmed
Chemistry Observations and Inferences

Test for Acidic Radicals CH3COO–

S.No. Treatment Observation Inference
1 Salt + dil. H2SO4 + Heat Colourless vinegar like smell gas Weak acidic group present CH3COO– may be
2 Confirmatory test
Sodium carbonate extract + neutral FeCl3 Solution		 Reddish coloured solution is obtained CH3COO– is confirmed
Salt + Oxalic acid + 2-3 drops water and rub Vinegar smell CH3COO– is confirmed

Chemistry Observations and Inferences

Test for Acidic Radicals NO2–

S.No. Treatment Observation Inference
1 Salt + dil. H2SO4 + Heat Reddish brown gas with pungent smell is evolved Weak acidic group present NO2– may be
2 Confirmatory test
Sodium carbonate extract + dil. H2SO4 + freshly prepared FeSO4 solution		 The solution colour changed to black NO2– is confirmed
Bring a filter paper wetted with dil. H2SO4 + KI and starch solution to the mouth of test tube Filter paper turns blue NO2– is confirmed

Chemistry Observations and Inferences

Test for Acidic Radicals S2-

S.No. Treatment Observation Inference
1 Salt + dil. H2SO4 + Heat Colourless, gas with Rotten egg smell Weak acidic group present S2- may be
Bring a filter paper wetted with dil. (CH3COO)2Pb solution to the mouth of test tube Filter paper turns black S2- is confirmed

Chemistry Observations and Inferences

Test for Acidic Radicals Br–

S.No. Treatment Observation Inference
1 Salt + dil. H2SO4 + Heat No reaction Weak acidic group absent
2 Salt + conc. H2SO4 + Heat Brownish coloured gas with pungent smell Strong acidic group present Br– may be
3 Confirmatory Test
Silvernitrate test		 Light yellow ppt. is formed which is partially soluble in excess of NH4OH Br– is confirmed
Layer Test:
Sodium carbonate extract + dil. HNO3 + CHCl3 + Cl2 water + shake it		 Layer of CHCl3 changed to brownish Br– is confirmed

Observations and Inferences

Test for Acidic Radicals Cl–

S.No. Treatment Observation Inference
1 Salt + dil. H2SO4 + Heat No reaction Weak acidic group absent
2 Salt + conc. H2SO4 + Heat Colourless gas with pungent smell Strong acidic group present Cl– may be
3 Confirmatory Test
Silvernitrate test		 White ppt. is formed which is soluble in excess of NH4OH Cl– is confirmed
4 Chromyl chloride test
Salt + solid K2Cr2O7 + conc. H2SO4 + Heat		 Dark reddish brown gas is evolved Cl– is confirmed
Pass the evolved gas in NaOH solution Solution of NaOH changes to yellow colour Cl– is confirmed
The above solution + CH3COOH + (CH3COO)2Pb Yellow ppt is formed Cl– is confirmed

Chemistry Observations and Inferences

Test for Acidic Radicals I–

S.No. Treatment Observation Inference
1 Salt + dil. H2SO4 + Heat No reaction Weak acidic group absent
2 Salt + conc. H2SO4 + Heat Violet coloured gas with pungent smell Strong acidic group present I– may be
3 Confirmatory Test
Silvernitrate test		 Dark yellow ppt. is formed which is insoluble in excess of NH4OH I– is confirmed
Layer Test:
Sodium carbonate extract + dil. HNO3 + CHCl3 + Cl2 water + shake it		 Layer of CHCl3 changed to violet I– is confirmed

Chemistry Observations and Inferences

Test for Acidic Radicals NO3–

S.No. Treatment Observation Inference
1 Salt + dil. H2SO4 + Heat No Reaction Weak acidic group absent
2 Salt + conc. H2SO4 + Heat Reddish brown gas with pungent smell Strong acidic group present NO3– may be
3 Confirmatory Test
Ring test – Sodium carbonate extract + freshly prepared solution of FeSO4 + conc. H2SO4 along the sides of the test tube		 A dark brown ring is formed at the junction of the layers of the two solutions NO3– is confirmed

Chemistry Observations and Inferences

Test for Acidic Radicals SO4–

S.No. Treatment Observation Inference
1 Salt + dil. H2SO4 + Heat No reaction Weak acidic group absent
2 Salt + conc. H2SO4 + Heat No reaction Strong acidic group absent
3 Sodium carbonate extract + dil. HCl + BaCl2 solution White ppt. is formed SO42- may be present
4 Confirmatory test:
Dissolve the above ppt in conc. HCl / conc. HNO3		 Ppt is insoluble SO42- confirmed
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