Carboxylic Acids & Esters

Question 1

Name the functional group on carboxylic acids

Answer 1

COOH

C=O O-H

Question 2

Which is more polar, a carbonyl, an alcohol or a carboxylic acid?

Answer 2

Carboxylic acid due to the -OH Hydroxyl group & the C=O

Question 3

How do we name carboxylic acids?

Answer 3

Take the -e from the end of the named alkane and replace with a -oic acid

Question 4

What is needed to produce an aldehyde?

Answer 4

Primary alcohol oxidised using K2Cr2O7 with H2SO4

Question 5

How is a carboxylic acid produced?

Answer 5

Oxidising a primary alcohol using K2Cr2O7 with H2SO4 to produce aldehyde & then reflux to produce carboxylic acid

Question 6

In the presence of acidified potassium dichromate and dilute sulphuric acid, what is the positive result observation for an aldehyde?

Answer 6

Orange to green

Question 7

Using tollen’s reagent, what is the positive result for an aldehyde?

Answer 7

Silver mirror

Question 8

What is produced when an alkali and acid are mixed?

Answer 8

Salt + water

Question 9

What is produced if an acid and a carbonate are mixed?

Answer 9

Salt + water + CO2

Question 10

Why are carboxylic acids soluble?

Answer 10

Water molecules form hydrogen bonds with acid molecules meaning they dissolve in water

Question 11

Why do longer hydrocarbons become less soluble the larger the chain in water?

Answer 11

The hydrocarbon tail gets in the way of the hydrogen bonds and therefore break them, being replaced with weaker VdW’s

Question 12

When is the carboxylate ion produced?

Answer 12

When a carboxylic acid and an alkali are mixed to produce a carboxylate ion and water

Question 13

What is produced if an acid and metal are reacted?

Answer 13

Salt + hydrogen gas

Question 14

What occurs when a weak acid is dissolved in water?

Answer 14

Equilibrium occurs

Question 15

What is required to make an ester?

Answer 15

Carboxylic acid and alcohol
Or
acid anhydride and and alcohol

Question 16

What are esters used for?

Answer 16

Flavourings, perfumes etc.

Question 17

Which functional group does an ester contain?

Answer 17

Cooc

Question 18

Which catalyst is required in the production of an ester?

Answer 18

Concentrated H2SO4

Question 19

When producing the ester, which parts come from each component?

Answer 19

H from carboxylic acid and OH from alcohol removed to form water waste product. The remaining bonds form together to produce an ester

Question 20

When naming esters, which part comes from ‘yl’ and which from the ‘oate’

Answer 20

Yl - alcohol

Oate - carboxylic acid

Question 21

What is esterification?

Answer 21

Formation of esters removing water

Question 22

What is hydrolysis of esters?

Answer 22

Break up of esters by addition of water

Question 23

Aside from alcohol + carboxylic acid, what is a less common way to produce esters?

Answer 23

Alcohol + acid anhydride

Question 24

Which is more polar, an alcohol, a carbonyl or a carboxylic acid and why?

Answer 24

Carboxylic acid because it contains both a hydroxyl group and a carbonyl group

Question 25

Define the term acid

Answer 25

A proton donor (donates H+ ions)

Question 26

Why are carboxylic acids defined as weak acids?

Answer 26

They only partially dissociate

Question 27

Write a fully balanced equation between ethanoic acid and sodium hydroxide

Answer 27

CH3COOH + NaOH –> CH3COO-Na+ + H2O

Question 28

What is observed when metals react with acids?

Answer 28

Effervescence

Question 29

Are carboxylic acids soluble? If so, why?

Answer 29

Yes, because hydrogen bonds are formed between water molecules and individual molecules of acid

Question 30

Is esterification reversible?

Answer 30

Yes, hydrolysis of esters is the reverse reaction

Question 31

Which of the following cannot be reduced; ketones, carboxylic acids and aldehydes

Answer 31

Carboxylic acids