Reactions With Carbonyl Groups

Question 1

What are aldehydes oxidised to?

Answer 1

Carboxylic acids

Question 2

What symbol represents an oxidising agent?

Answer 2

[O]

Question 3

What oxidising agent oxidised aldehydes?

Answer 3

Acidified potassium dichromate (VI)

Question 4

How do we acidify potassium dichromate (VI)?

Answer 4

Add excess dilute sulfuric acid

Question 5

What two tests distinguish an aldehyde from a ketone?

Answer 5

-Fehlings Test
-Tollens Reagent/Silver Mirror Test

Question 6

How is Fehlings test used to identify an aldehyde?

Answer 6

1. aldehyde warmed with Fehlings solution
2. Brick red precipitate formed
3. Cu (II) oxidises aldehyde and itself is reduced to Cu (I)

Question 7

How is Tollens Reagent/ The silver mirror test used to identify an aldehyde?

Answer 7

1. Aldehyde warmed with Tollens Reagent
2. Metallic silver formed, produced mirror on inside of test tube
3. Ag+ reduced to metallic silver

Question 8

What equation shows how Tollens Reagent is reduced to metallic silver?

Answer 8

[Ag(NH3)2]+ + e- > Ag + 2NH3

Question 9

What is a hydroxynitrile?

Answer 9

contains hydroxyl and nitrile group

Question 10

Which is the highest priority group between hydroxyl and nitrile?

Answer 10

C=-N

Question 11

How do we name hydroxynitriles?

Answer 11

name from nitrile, including C in C=-N bond as the start of the carbon chain

Question 12

What is the symbol for a cyanide ion?

Answer 12

:CN-

Question 13

What will the reaction of a cyanide ion and aldehyde produce?

Answer 13

Hydroxynitrile
Racemic mixture of two optical isomers (enantiometers)

Question 14

Why can nucleophillic addition lead to a racemic mixture with a cyanide ion?

Answer 14

:CN- can attack from above and below planar C=O

Question 15

How can an optical isomer arise in a hydroxynitrile?

Answer 15

-chiral carbon
-asymmetrical
-two different R groups

Question 16

What is a chiral carbon?

Answer 16

carbon attached to four different types of atoms

Question 17

What is a racemic mixture?

Answer 17

equal quantities of each enantiometer in a mixture

Question 18

What are the shape of double bonds?

Answer 18

Planar

Question 19

What are the hazards of potassium cyanide?

Answer 19

toxic/poisonous
flammable

Question 20

As potassium cyanide is flammable what is used instead of a Bunsen burner?

Answer 20

Water Bath

Question 21

Why is potassium cyanide acidified?

Answer 21

Produce H+ ions

Question 22

What are the hazards of hydrogen cyanide?

Answer 22

extremely poisonous
flammable
hard to store as gas

Question 23

How do Carboxylic acids react?

Answer 23

-C+ open to attack from nucleophiles
-O- of C=O attacked by positively charged species (H+)

Question 24

How is a carboxylate ion formed?

Answer 24

hydrogen of OH group lost leaving a negative carboxylate ion

Question 25

What do reactions with Carboxylic acids form?

Answer 25

ionic salts / carboxylate ion Water Carbon dioxide with a metal carbonate

Question 26

How do Carboxylic acids form ionic salts?

Answer 26

by reacting with more reactive metals, alkalis, metal oxides or metal carbonates

Question 27

How does ethanoic acid react with sodium hydroxide?

Answer 27

CH3COOH (aq) + NaOH (aq) > CH3COONa (aq) + H2O (l)

Question 28

What is the word equation to show how sodium hydroxide reacts with ethanoic acid?

Answer 28

ethanoic acid + sodium hydroxide > sodium ethanoate + water

Question 29

How does ethanoic acid react with sodium carbonate?

Answer 29

2CH3COOH (aq) + Na2CO3 (aq) > 2CH3COONa (aq) + H2O (l) + CO2 (g)

Question 30

What is the word equation for the reaction between ethanoic acid and sodium carbonate?

Answer 30

ethanoic acid + sodium carbonate > sodium ethanoate + water + carbon dioxide

Question 31

How are esters formed?

Answer 31

Carboxylic acid reacts with alcohol alongside strong acid catalyst (concentrated H2SO4)

Question 32

How is an ester hydrolysed?

Answer 32

C+ attacked by weak nucleophile in carbonyl bond

Question 33

What does ester hydrolysis form?

Answer 33

Carboxylic acid Alcohol

Question 34

What conditions are required for ester hydrolysis?

Answer 34

reflux strong acid catalyst lots of water

Question 35

Why is lots of water needed in ester hydrolysis?

Answer 35

push equilibrium to right

Question 36

What word equation shows how an ester and base react?

Answer 36

carboxylate ion/ionic salt + alcohol

Question 37

What are the conditions for a base/ester reaction?

Answer 37

reflux hydroxide base reaction in completion