Alcohols, Carboxylic Acids and Esters

Question 1

What is the general formula of an alcohol?

Answer 1

CₙH₂ₙ₊₁OH

Question 2

What functional group do all alcohols contain?

Answer 2

-OH functional group

Question 3

What is the formula of an alcohol with 2 carbon atoms?

Answer 3

C₂H₅OH

Question 4

What series do alcohols belong to?

Answer 4

Homologous series

Question 5

Can the -OH group be attached to different carbon atoms?

Answer 5

Yes, it is possible to get alcohols where the -OH group is attached to different carbon atoms in the carbon chain.

Question 6

Can alcohols have more than one -OH group?

Answer 6

Yes, like the ones that form condensation polymers.

Question 7

What happens when something is oxidised?

Answer 7

It gains oxygen

Question 8

What do alcohols form when oxidised?

Answer 8

Carboxylic acids

Question 9

What is used to oxidise alcohols?

Answer 9

Potassium dichromate(VI) in dilute sulfuric acid

Question 10

What colour change is observed when alcohol is oxidised?

Answer 10

Orange to green

Question 11

When can alcohols be oxidised this way?

Answer 11

Only if the -OH group is attached to a carbon that’s only attached to one carbon itself.

Question 12

How do some microorganisms use alcohols?

Answer 12

As an energy source

Question 13

What do they use to oxidise alcohols? microorganisms

Answer 13

Oxygen in the air

Question 14

What is the by-product of microbial oxidation of alcohols?

Answer 14

Carboxylic acids

Question 15

Give an example of microbial oxidation.

Answer 15

Oxidation of ethanol produces ethanoic acid

Question 16

What happens when alcohols are burnt in oxygen?

Answer 16

Complete combustion

Question 17

What are the products of this reaction?

Answer 17

Water and carbon dioxide

Question 18

What is the word equation for ethanol combustion?

Answer 18

Ethanol + oxygen → carbon dioxide + water

Question 19

How is ethene produced?

Answer 19

From crude oil by cracking

Question 20

What does ethene react with to form ethanol?

Answer 20

Steam (H₂O)

Question 21

What kind of reaction is it?

Answer 21

Addition reaction

Question 22

What conditions are needed?

Answer 22

300°C, 60–70 atm, phosphoric acid catalyst

Question 23

Is this process currently cheap?

Answer 23

Yes, because ethene’s fairly cheap and not much is wasted

Question 24

What is a disadvantage of this method?

Answer 24

Crude oil is non-renewable, so it will become expensive

Question 25

What is the raw material for fermentation?

Answer 25

Sugar, e.g. glucose

Question 26

What organism is used?

Answer 26

Yeast

Question 27

What are the products of fermentation?

Answer 27

Ethanol and carbon dioxide

Question 28

What type of catalyst is in yeast?

Answer 28

Enzyme (a naturally occurring catalyst)

Question 29

What temperature is needed?

Answer 29

About 30°C

Question 30

What happens if the mixture gets too hot?

Answer 30

The enzyme denatures and the reaction stops

Question 31

What conditions are needed?

Answer 31

Anaerobic (no oxygen)

Question 32

Why avoid oxygen in fermentation?

Answer 32

It turns ethanol into ethanoic acid (vinegar)

Question 33

What is an advantage of fermentation?

Answer 33

Raw materials are renewable

Question 34

What are disadvantages of fermentation?

Answer 34

Ethanol is not very concentrated, needs distillation and purification

Question 35

What functional group do carboxylic acids have?

Answer 35

-COOH

Question 36

What series do they belong to?

Answer 36

Homologous series

Question 37

What are the first four carboxylic acids?

Answer 37

Methanoic acid, ethanoic acid, propanoic acid, butanoic acid

Question 38

What do carboxylic acids form when they react like other acids?

Answer 38

Salts that end in -anoate

Question 39

What do they form with metal carbonates?

Answer 39

Salt, water and carbon dioxide

Question 40

Give an example of reaction with sodium carbonate:

Answer 40

Ethanoic acid + sodium carbonate → sodium ethanoate + water + carbon dioxide

Question 40

What do carboxylic acids form with metals?

Answer 40

Salt and hydrogen

Question 41

Give an example with magnesium:

Answer 41

Ethanoic acid + magnesium → magnesium ethanoate + hydrogen

Question 42

What other use do carboxylic acids have?

Answer 42

Used in the preparation of esters

Question 43

How is ethanoic acid made?

Answer 43

By oxidising ethanol (microbes or oxidising agents)

Question 44

What happens if you leave wine open?

Answer 44

Ethanol in it is oxidised

Question 45

How is vinegar made?

Answer 45

Ethanoic acid dissolved in water

Question 46

What functional group do esters have?

Answer 46

-COO-

Question 47

How are esters formed?

Answer 47

From an alcohol and a carboxylic acid

Question 48

What is the general word equation for making an ester?

Answer 48

alcohol + carboxylic acid → ester + water

Question 49

What is usually used as a catalyst in ester formation?

Answer 49

An acid catalyst (e.g. concentrated sulfuric acid)

Question 50

What do ester names end in?

Answer 50

'-oate'

Question 51

Which part of the name comes from the alcohol?

Answer 51

The first part

Question 52

Which part of the name comes from the acid?

Answer 52

The second part

Question 53

Give an example: ethanol + ethanoic acid → ?

Answer 53

Ethyl ethanoate + water

Question 54

Give another example: methanol + propanoic acid → ?

Answer 54

Methyl propanoate + water

Question 55

What type of reaction is used to make esters in the lab?

Answer 55

The reaction between alcohols and carboxylic acids

Question 56

What is the first step when making ethyl ethanoate in the lab?

Answer 56

Add a few drops of concentrated sulfuric acid to a boiling tube using a dropping pipette

Question 57

What do you add after the sulfuric acid?

Answer 57

About 10 drops of ethanoic acid

Question 58

What do you add after ethanoic acid?

Answer 58

An equal volume of ethanol

Question 59

What do you do with the boiling tube after adding the chemicals?

Answer 59

Place the boiling tube in a beaker of water and place on a tripod

Question 60

How do you heat the reaction mixture?

Answer 60

Heat using a Bunsen burner until the water starts to boil, then turn off the Bunsen

Question 61

What should you do after heating for 1 minute?

Answer 61

Remove the tube and allow it to cool

Question 62

What observation indicates the ester has formed?

Answer 62

A layer of the ester should form on top of the solution

Question 63

What should the ester smell like?

Answer 63

Sweet, like pear drops

Question 64

What do many esters smell like?

Answer 64

Pleasant, often quite sweet and fruity

Question 65

Are esters volatile?

Answer 65

Yes — they evaporate (turn into gases) easily

Question 66

Why are esters used in perfumes?

Answer 66

Because the evaporated molecules can be detected by smell receptors in your nose

Question 67

Why are esters used in food flavourings?

Answer 67

Because there are esters that smell or taste of rum, apple, orange, banana, grape, pineapple, etc.

Question 68

Structural formula of Methanoic acid

Answer 68

HCOOH

Question 69

Structural formula of Ethanoic acid

Answer 69

CH3COOH

Question 70

Structural formula of Propanoic acid

Answer 70

CH3CH2COOH

Question 71

Structural formula of Butanoic acid

Answer 71

CH3CH2CH2COOH

Question 72

Structural formula of Pentanoic acid

Answer 72

CH3−CH2−CH2−CH2−COOH