Chapter 26 - Carbonyls and carboxylic acids

Question 1

What is the carbonyl functional group?

Answer 1

C=O

Question 2

What is the aldehyde group? (-al)

Answer 2

CHO

Question 3

What is the ketone group? (-one)

Answer 3

CO

Question 4

What product is made when you oxidise an aldehyde?

Answer 4

Carboxylic acid

Question 5

How do you oxidise an aldehyde?

Answer 5

Reflux with acidified dichromate ions and sulfuric acid

Question 6

What is the reactivity of aldehydes and ketones influenced by?

Answer 6

The nature of the carbon - oxygen double bond

Question 7

What reaction can carbonyl groups undergo?

Answer 7

Nucleophilic addition

Question 8

How does a nucleophile react with a carbonyl?

Answer 8

The nucleophile is attracted to and attacks the slightly positive carbon atom, resulting in addition across the C=O bond

Question 9

What happens when you reduce an aldehyde?

Answer 9

A primary alcohol is made

Question 10

What happens when you reduce a ketone?

Answer 10

A secondary alcohol is made

Question 11

What do you use in the reduction of a carbonyl?

Answer 11

NaBH4, water and heat

Question 12

How are oxidation agents represented in an equation?

Answer 12

[O]

Question 13

How are reduction agents represented in an equation?

Answer 13

[H]

Question 14

What is produced when an aldehyde is reduced using HCN?

Answer 14

A hydroxynitrile (with a CN triple bond)

Question 15

What is HCN?

Answer 15

Hydrogen cyanide is a poisonous liquid which can is used as a means of increasing the length of the carbon chain

Question 16

What are the two catalysts in a HCN reduction reaction?

Answer 16

H2SO4 and NaCN

Question 17

What is used to detect the presence of the carbonyl functional group?

Answer 17

Brady’s reagent (clear to orange)

Question 18

What can be used to distinguish between an aldehyde and a ketone after identifying a carbonyl group?

Answer 18

Tollen’s reagent (solution of silver nitrate in aqueous ammonia) which forms a silver mirror precipitate with the presence of an aldehyde group

Question 19

What is a carboxyl functional group?

Answer 19

A carbonyl group and a hydroxyl group

Question 20

Which carbon atom is a carboxyl group designated to?

Answer 20

Carbon-1

Question 21

Describe the solubility of carboxylic acids

Answer 21

• C=O and O-H bonds are polar and so they dissolve in water
• As the number of carbon atoms increases, the solubility decreases (non-polar chain has a greater effect on the overall polarity of the molecule)

Question 22

What kind of acid is a carboxylic acid?

Answer 22

Weak acids

Question 23

What reactions do carboxylic acids take part in?

Answer 23

Neutralisation (with bases/ alkalis, metal oxides, carbonates) and redox (with metals)

Question 24

What happens to the suffix of a carboxylic acid when it reacts?

Answer 24

-ic acid becomes -ate (carboxylic to carboxylate)

Question 25

What happens when a carboxylic acid reacts with metals in a redox reaction?

Answer 25

A carboxylate salt and hydrogen gas is produced (metal disappears and effervescence produced)

Question 26

What happens when a carboxylic acid reacts with a metal oxide?

Answer 26

A salt and water is produced

Question 27

What happens when a carboxylic acid reacts with an alkali?

Answer 27

A salt and water is produced (H+ + OH- > H2O)

Question 28

What happens when a carboxylic acid reacts with a carbonate?

Answer 28

A salt, water and carbon dioxide is produced

Question 29

What is a derivative of a carboxylic acid?

Answer 29

A compound that can be hydrolysed to form the parent carboxylic acid

Question 30

What is present in carboxylic acid derivatives?

Answer 30

An acyl group (common sequence of atoms in their sequence)

Question 31

Give some examples of carboxylic acid derivatives

Answer 31

Esters, acyl chlorides, acid anhydrides and amides

Question 32

What happens when a carboxylic acid becomes an ester?

Answer 32

The hydrogen of OH is removed and replaced by another element (eg. Cl/ Br)

Question 33

What happens when two carboxylic acids react?

Answer 33

They form an acid anhydride aswell as H2O

Question 34

What is esterification?

Answer 34

The reaction between alcohol and a carboxylic acid to form an ester and water

Question 35

What is required for esterification to occur?

Answer 35

Warm temperatures and concentrated H2SO4 (catalyst)

Question 36

How can you change an ester into a carboxylic acid?

Answer 36

Acid hydrolysis by heating an ester under reflux with dilute aqueous acid

Question 37

What are the products of acid hydrolysis?

Answer 37

A carboxylic acid and an alcohol