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Question : 11
Total: 12
(a) (i) Which acid of the following pair would you except to be stronger?
F − CH 2 − COOH or CH 3 − COOH
(ii) Arrange the following compounds in increasing order of their boiling points:
CH 3 CH 2 OH , CH 3 − CHO . CH 3 − COOH
(iii) Give simple chemical test to distinguish between Benzaldehyde and Acetophenone.
OR
(b) (i) Which will undergo faster nucleophilic addition reaction?
Acetaldehyde Propanone
(ii) What is the composition of Fehling's reagent?
(iii) Draw structure of the semicarbazone of Ethanal.
(ii) Arrange the following compounds in increasing order of their boiling points:
(iii) Give simple chemical test to distinguish between Benzaldehyde and Acetophenone.
OR
(b) (i) Which will undergo faster nucleophilic addition reaction?
Acetaldehyde Propanone
(ii) What is the composition of Fehling's reagent?
(iii) Draw structure of the semicarbazone of Ethanal.
Solution:
(a) (i) Among FCH 2 COOH CH 3 COOH FCH 2 COOH
(ii) The increasing order of boiling point in the following compounds is
CH 3 CHO < CH 3 CH 2 OH < CH 3 COOH
Ethanoicacid and ethanol hascomparatively higher boiling point than ethanal as they both are held by strong hydrogen bonds in between them whereas in ethanal there is dipole-dipole interaction in between them.
(iii) With ammoniacal silver nitrate solution (Tollen's reagent), benzaldehyde forms silver mirror but acetophenone does not give this test.
C 6 H 5 CHO + 2 [ Ag ( NH 3 ) 2 + + 3 OH − → C 6 H 5 COO − + 2 Ag ↓ + 4 NH 3 + 2 H 2 O
Acetophenone gives positive iodoform test whereas benzaldehyde do not give iodoform test.
+
→
+
+ 2 NaOH
(yellow ppt)
+ NaOI → CH 3
OR
(b) (i) Aldehydes are generally more reactive than ketones in nucleophilic addition reactions due to steric hindrance. As the electron density at carbonyl carbon increases,+ I
(ii) Fehling's solution is a mixture of alkaline solution of copper(II) sulphate( CuSO 4 ) KNaC 4 H 4 O 6 ⋅ 4 H 2 O
(iii) Structure of semi carbazone from ethanal.
(ii) The increasing order of boiling point in the following compounds is
Ethanoicacid and ethanol hascomparatively higher boiling point than ethanal as they both are held by strong hydrogen bonds in between them whereas in ethanal there is dipole-dipole interaction in between them.
(iii) With ammoniacal silver nitrate solution (Tollen's reagent), benzaldehyde forms silver mirror but acetophenone does not give this test.
Acetophenone gives positive iodoform test whereas benzaldehyde do not give iodoform test.
(yellow ppt)
OR
(b) (i) Aldehydes are generally more reactive than ketones in nucleophilic addition reactions due to steric hindrance. As the electron density at carbonyl carbon increases,
(ii) Fehling's solution is a mixture of alkaline solution of copper(II) sulphate
(iii) Structure of semi carbazone from ethanal.
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