Unit 2: (d) Esters, fats, and olis

Question 1

What are 3 uses of esters?

Answer 1

Food flavouring, Perfumes, Solvents.

Question 2

How are esters made?

Answer 2

By joining an alcohol and carboxylic acid.

Question 3

Making an ester is an example of what kind of reaction?

Answer 3

A condensation reaction.

Question 4

What is the word equation for making an ester?

Answer 4

Carboxylic + alcohol -> ester + water

acid

Question 5

What is the definition of a condensation reaction?

Answer 5

When 2 or more small molecules join together to form a larger molecule with the elimination of a smaller molecule e.g. water.

Question 6

What is the definition of a hydrolysis reaction?

Answer 6

The breaking down of a larger molecule into smaller molecules by reaction with water.

Question 7

Is making an ester a reversible process?

Answer 7

Yes.

Question 8

What catalyst is used to make an ester and why?

Answer 8

Sulphuric acid acts as a catalyst as it provides H+ ions.

Question 9

What is the first part of an esters name taken from?

Answer 9

The alcohol used to make it.

Question 10

What is the second part of an esters name taken from?

Answer 10

The acid used to make it.

Question 11

Ethanoic acid and methanol will react to create what ester?

Answer 11

Methyl-ethanoate

Question 12

What is the reflux apparatus used for in the hydrolysis of an ester?

Answer 12

To break down the ester into the salt and alcohol.

Question 13

What is the distillation apparatus used for in the hydrolysis of an ester?

Answer 13

Separate the salt from the alcohol.

Question 14

What are the salts formed in the hydrolysis of esters used for?

Answer 14

Soaps.

Question 15

What are esters hydrolysed to?

Answer 15

Alcohols and carboxylic acids.

Question 16

What type of molecule are fats and oils?

Answer 16

Esters.

Question 17

What do fats and oils do?

Answer 17

Provide energy to plants and animals.

Question 18

What is the alcohol present in fats and oils?

Answer 18

Glycerol.

Question 19

What is the chemical name for glycerol?

Answer 19

Propan-1,2,3-triol.

Question 20

How can fats an oils be classified? Give 3 examples.

Answer 20

Fats and oils can be classified according to there origin. Plant, Animal, Marine.

Question 21

Why is glycerol classed as a triol?

Answer 21

It contains 3 hydroxyl groups.

Question 22

How many carboxylic acids can each OH group combine with?

Answer 22

1.

Question 23

What can fats and oils be described as?

Answer 23

Triglycerides.

Question 24

How many moles of glycerol and acids do fats and oils contain?

Answer 24

One mole of propan-1,2,3-triol and 3 moles of long chain acids.

Question 25

What are the acids in fats and oils said to be?

Answer 25

Long chain fatty acids.

Question 26

Why can the acids in fats and oils be described as long chain?

Answer 26

They contain lots of Carbons in a chain.

Question 27

Why can the acids in fats and oils be described as fatty?

Answer 27

They come from fats and oils.

Question 28

What is the number of carbons in a long chain fatty acid always?

Answer 28

Even.

Question 29

What can fats and oils be hydrolysed to?

Answer 29

One mole of glycerol and 3 moles of fatty acids.

Question 30

Why are fats solid at room temperature? (explain fully)

Answer 30

They contain carbon to carbon single bonds which means that they are more flexible so;
They pack together closely so;
They have larger Van Der Waals forces so;
They have higher melting and boiling points.

Question 31

Why are oils liquid at room temperature? (explain fully)

Answer 31

They contain carbon to carbon double bonds which means that they are not very flexible so;
They cannot pack together closely so;
They have weaker Van Der Waals forces so;
They have lower melting and boiling points.

Question 32

Why are unsaturated oils often reacted with hydrogen?

Answer 32

To harden them.

Question 33

What catalyst is used in the hydrogenation of oils?

Answer 33

Nickle catalyst.

Question 34

How does adding hydrogen harden the oils?

Answer 34

The hydrogen adds across the double bond and turns it into a saturated fat allowing the molecules to pack more tightly together.

Question 35

What is the process of adding hydrogen to unsaturated oils known as?

Answer 35

Hardening, Hydrogenation, Addition.