aldehydes and ketones

Question 1

oxidising agent (oxidation of alcohols)

Answer 1

K2Cr2O7 (potassium dichromate) or KMNO4 (potassium manganate)

Question 2

reducing agent (oxidation of alcohols)

Answer 2

NaBH4 (sodium borohydride) or LiAlBH4 (lithium aluminium hydride)

Question 3

colour change of CrO7^2- to Cr^3+

Answer 3

orange to green

Question 4

colour change of MnO4^- to Mn^2+

Answer 4

purple to colourless

Question 5

product of nucleophillic addition with HCN

Answer 5

hydroxynitriles

Question 6

nucleophilic addition steps

Answer 6

1. nucleophilic attack
2. potronation

Question 7

oxidising agent in fehling’s solution

Answer 7

Cu^2+ (copper (II) ions)

Question 8

colour change of cu^2+ to cu^+

Answer 8

blue to opaque (red precipitate)

Question 9

oxidising agent of tollen’s reagent

Answer 9

Ag^+ in ammoniacal silver nitrate solution

Question 10

colour change of Ag^+ to Ag

Answer 10

silver mirror inside tube

Question 11

what happens in alkaline solution for both fehling and tollen’s test

Answer 11

carboxylic acid becomes carboxylate ion and will form a salt

Question 12

product of iodoform reaction

Answer 12

CHI3 (yellow precipitate) + salt

Question 13

steps of iodoform reaction

Answer 13

1. halogenation (I2, NaOH)
2. hydrolysis (NaOH)

Question 14

use of 2,4 -DNPH

Answer 14

test for presence of carbonyl compounds

Question 15

aldehyde and ketones undergo what reaction with 2,4-DNPH

Answer 15

condensation

Question 16

product of reaction with 2,4-DNPH with aldehyde/ketone

Answer 16

deep orange precipitate