Page 55 - Lab Manual & Project class 12
P. 55
SYSTEMATIC QUALITATIVE ANALYSIS
–
(ii) NO + CH COOH HNO + CH COO –
2 3 2 3
2HNO + 2KI + 2CH COOH 2CH COOK + 2H O + 2NO + I
2 3 3 2 2
I + Starch Blue complex
2
(b) Sulphanilic acid — 1-naphthylamine reagent test (Griss-Ilosvay test)
On adding sulphanilic acid and 1-naphthylamine reagent to the water
extract or acidified with acetic acid, sulphanilic acid is diazotised in the
reaction by nitrous acid formed. Diazotised acid couples with
1-naphthylamine to form a red azo-dye.
–
NO + CH COOH HNO + CH COO –
3
2
2
3
Maxbrain Chemistry
The test solution should be very dilute. In concentrated solutions
reaction does not proceed beyond diazotisation.
–
5. Test for Acetate ion [CH COO ]
3
(a) If the salt smells like vinegar on treatment with dil. H SO , this indicates
4
2
the presence of acetate ions. Take 0.1 g of salt in a china dish and
add 1 mL of ethanol. Then add about 0.2 mL of conc. H SO and heat.
2
4
–
Fruity odour of ethyl acetate indicates the presence of CH COO ion.
3
2 CH COONa + H SO 4 Na SO + 2 CH COOH
2
3
3
2
4
CH COOH + C H OH H + CH COOC H + H O
3
5
2
3
2
2
5
Ethylacetate
(Fruity odour)
55
24-04-2018
