EXPERIMENT 8: IDENTIFICATION OF ALDEHYDES AND KETONES

Question 1

are representative of compounds which possess the carbonyl group

Answer 1

ALDEHYDES AND KETONES

Question 2

have at least one hydrogen attached to the carbonyl carbon

Answer 2

ALDEHYDES

Question 3

No hydrogen attached to the carbonyl carbon, only carbon containing R-groups

Answer 3

KETONES

Question 4

(TRUE/FALSE) Aldehydes and ketones of low molecular weight have commercial importance.

Answer 4

TRUE

Question 5

Oxidation of methanol; plastics; preservatives

Answer 5

FORMALDEHYDE

Question 6

Oxidation of isopropyl alcohol; solvent

Answer 6

ACETONE

Question 7

Lemon grass oil; fragrance

Answer 7

CITRAL

Question 8

Oil of jasmine; fragrance

Answer 8

JASMONE

Question 9

Aldehydes are oxidized to carboxylic acids; ketones are not oxidized.

Answer 9

CHROMIC ACID TEST

Question 10

(TRUE/FALSE) A positive test is the formation of a blue-green solution from the brown-red color of chromic acid.

Answer 10

TRUE

Question 11

Tollen’s reagent

Answer 11

ammonia and silver nitrate

Question 12

This test is sometimes referred to as the “silver mirror” test.

Answer 12

TOLLEN’S TEST

Question 13

(TRUE/FALSE) Most aldehydes reduce Tollen’s reagent to give a precipitate of silver metal.

Answer 13

TRUE

Question 14

In Tollen’s test, the aldehyde is oxidized to a ____________.

Answer 14

CARBOXYLIC ACID

Question 15

Benedict’s reagent

Answer 15

a citrate complex of Cu(II) ion in a base solution

Question 16

Alipathic aldehydes are oxidized to carboxylic acids with Benedict’s reagent.

Answer 16

BENEDICT’S TEST

Question 17

(TRUE/FALSE) The Cu (II) ion is reduced to Cu (I) ion and its oxide, Cu2O, precipitates as brick-red solid.

Answer 17

TRUE

Question 18

(TRUE/FALSE) In Benedict’s test, aromatic aldehydes and ketones react, forming a brick-red precipitate.

Answer 18

FALSE (they do not react; thus, no precipitate is formed)

Question 19

(TRUE/FALSE) Methyl ketones give the yellow precipitate iodoform when reacted with iodine in aqueous sodium hydroxide

Answer 19

TRUE

Question 20

Alcohols do not give this test.

Answer 20

2,4-Dinitrophenylhydrazine test

Question 21

All aldehydes and ketones give an immediate precipitate with 2,4 dinitrophenylhydrazine reagent. The reaction varies from yellow to red.

Answer 21

2,4-Dinitrophenylhydrazine test

Question 22

4 Compounds involved in experiment 8

Answer 22

ISOVALERALDEHYDE,
BENZALDEHYDE,
CYCLOHEXANONE,
ACETONE,
UNKNOWN

Question 23

(TRUE/FALSE) Chromic acid are non-corrosive.

Answer 23

FALSE (THEY ARE CORROSIVE)