Confirmatory Tests

Question 1

Confirmatory test for carbonate

Answer 1

Lime water test:
Salt + Dil. H2SO4, pass the gas into lime water –> lime water turns milky
If excess of CO2 passed –> milkiness disappears

Question 2

Confirmatory test for chloride
Chromyl chloride

Answer 2

a) Chromyl chloride test:
Salt + K2Cr2O7 (solid in a small amt) in a dry test tube + Conc. H2SO4 –>
Reddish brown pungent smelling vapours are evolved

The vapours are dissolved in NaOH solution –> yellow solution

Yellow solution+ Dil. Acetic acid+ lead acetate solution–> yellow ppt

Question 3

Confirmatory test for chloride
Silver nitrate

Answer 3

Salt solution + Dil HNO3 + AgNO3 solution –> curdy white ppt insoluble in ammonium hydroxide

Question 4

Confirmatory test for bromide
Globule test

Answer 4

Salt solution+ CCl4 + chlorine water, shaken well –> orange red globule separates out

Question 5

Confirmatory test for bromide
Silver nitrate test

Answer 5

Salt solution+ Dil HNO3+ AgNO3 solution –> pale yellow ppt

To the pale yellow ppt, add ammonium hydroxide soln
–> pale yellow ppt is sparingly soluble

Question 6

Confirmatory test for Nitrate
Copper turning test

Answer 6

Salt + copper turning+ conc. h2SO4, heat –> reddish brown pungent gas is evolved and soln becomes green

Question 7

Confirmatory test for Nitrate
Brown ring test

Answer 7

Salt solution + freshly prepared Ferrous sulphate solution+ conc. H2SO4 dropwise along the side of the tt without disturbing the solution
–> a thin brown ring is formed at the junction of the two liquids

Question 8

Confirmatory test for sulphate
BaCl test

Answer 8

Barium chloride test:
Salt solution+ BaCl2 solution
–> a thick white ppt insoluble in dilute HCl

Question 9

Confirmatory test for sulphate
Lead acetate test

Answer 9

Salt solution+ acetic acid + lead acetate solution –> white ppt soluble in ammonium acetate solution