Unit 2: Chapter 5 - Alcohols, Carboxylic Acids and Esters

Question 1

What are alcohols?

Answer 1

Alcohols are a homologous series containing the functional group -OH. With The name ending -ol.

Question 2

What is ethanol commonly used in?

Answer 2

Alcoholic drinks.

Question 3

What is the prefix for 1?

Answer 3

Meth

Question 4

What is the prefix for 2?

Answer 4

Eth

Question 5

What is the prefix for 3?

Answer 5

Prop

Question 6

What is the prefix for 4?

Answer 6

But

Question 7

What is the prefix for 5?

Answer 7

Pent

Question 8

What is the prefix for 6?

Answer 8

Hex

Question 9

What is the prefix for 7?

Answer 9

Hept

Question 10

What is the prefix for 8?

Answer 10

Oct

Question 11

What is this the general formula of alcohols?

Answer 11

CnH2N+1OH

Question 12

What are alcohols containing two hydroxyl groups called?

Answer 12

Diols

Question 13

What are alcohols containing three hydroxyl groups called?

Answer 13

Triols

Question 14

What makes alcohols polar and what does this give rise to?

Answer 14

The hydroxyl group makes alcohols polar and this gives rise to hydrogen bonding.

Question 15

What can hydrogen bonding in alcohols be used to explain?

Answer 15

The properties of alcohols including B+M points, viscosity and solubility/miscibility in water.

Question 16

What is a carboxylic acid?

Answer 16

A carboxylic acid is a molecule containing the carboxyl functional group, ─COOH.

Question 17

what are carboxylic acids also known as?

Answer 17

Alkanoic acids.

Question 18

What is the general formula of the carboxylic acids?

Answer 18

CnH2nO2

Question 19

What is produced when a carboxylic acid reacts with a metal oxide?

Answer 19

A salt + water

Question 20

What is produced when a carboxylic acid reacts with a metal hydroxide?

Answer 20

A salt + water

Question 21

What is produced when a carboxylic acid reacts with a metal carbonate.

Answer 21

A salt + water + carbon dioxide

Question 22

What are uses of carboxylic acids?

Answer 22

Ethyl Ethanoate: Made from Ethanoic acid and when polymerised, used to give the plastic component in paints.

Benzene - 1,4 - dicarboxylic acid: A diacid in the manufacture of polyester.

Hexanedioic acid: Another diacid which is used as a monomer in the production of Nylon.

Benzoic acid: Used as a preservative and antioxidant in fruits.

Question 23

What is an ester?

Answer 23

A molecule containing an ester link ( -COO- ).

Question 24

How are esters formed?

Answer 24

By a condensation reaction between a carboxylic acid and an alcohol.

Question 25

What is the difference between the reactants and the products in the formation of esters?

Answer 25

Both reactants contain hydrogen bonding but the product contains no hydrogen bonding making it immiscible in water.

Question 26

In a condensation reaction two molecules are joined together with the elimination of what?

Answer 26

A small molecule. When an ester link is formed by the reaction between a hydroxyl group and a carboxyl group, the small molecule eliminated is water.

Question 27

What is the water made from in a condensation reaction between a carboxylic acid and an alcohol.

Answer 27

The water is made from the H of the hydroxyl group of the alcohol and the -OH group from the acid.

Question 28

What are esters most commonly used for?

Answer 28

Esters are used as flavourings and fragrances as many have pleasant, fruity smells. Esters are also used as solvents for non-polar compounds that do not dissolve in water.

Question 29

What does immiscible mean?

Answer 29

Incapable of being mixed.

Question 30

Are esters immiscible in water?

Answer 30

YES

Question 31

Describe the types of uses of esters?

Answer 31

- Esters are used in a variety of substances. Aspirin contains an ester link which has a bearing of the properties of the aspirin. - Nail varnish contains an ester which acts as a solvent and helps dissolve the coloured nail varnish is due to the ester which evaporates quickly after application. - Similar to nail varnish car metallic paint is dissolved in an ester solvent to keep the paint liquid. After application the ester evaporates to leave the hard durable metallic paint.

Question 32

What can be used to break down esters to form an alcohol and a carboxylic acid?

Answer 32

Hydrolysis

Question 33

What is a negative to using water to hydrolyse an ester?

Answer 33

Using water to break up an ester is very inefficient.

Question 34

What is more efficient to use than water to break up an ester and why is this?

Answer 34

Acid catalysed hydrolysis which is more efficient as the H+ ion is used as a catalyst. (remember that a dilute acid contains water).

Question 35

What is a negative about using acid catalysed hydrolysis to break up an ester?

Answer 35

It is reversible and therefore will be incomplete.

Question 36

What is the most efficient and complete way of break up an ester?

Answer 36

Complete hydrolysis by using a strong alkali.

Question 37

What are 2 advantages of Alkaline hydrolysis?

Answer 37

1) Alkaline hydrolysis is NOT REVERSIBLE and hence there should be a higher yield of products. 2) It is usually easier to separate the products using alkaline hydrolysis.

Question 38

What is the reaction equation for hydrolysis of an ester by water?

Answer 38

Ester + Water = Alcohol and Carboxylic Acid.

Question 39

What is the reaction equation for hydrolysis of an ester by by acid catalysed hydrolysis?

Answer 39

Ester + Acid = Alcohol + Carboxylic Acid + Acid.

Question 40

What is the theoretical reaction equation for hydrolysis of an ester by a strong alkali?

Answer 40

Ester + Alkali = Alcohol + Carboxylic Acid.

Question 41

What is the actual reaction equation for hydrolysis of an ester by a strong alkali and why is this?

Answer 41

Ester + Alkali = Alcohol + Salt of the Acid This is due to the ester being broken up into the alcohol and acid, the newly formed acid will be neutralised in the alkaline conditions to give the salt of the acid. For example: Ethyl Ethanoate + Alkali = Ethanol + Sodium Ethanoate CH3CH2OOCCH3 + NAOH = CH3CH2OH + NaOOCCH

Question 42

How can the products of alkaline hydrolysis be separated?

Answer 42

We can separate the products using distillation as the alcohol will have a lower boiling point than the dissolved salt of the acid. After distillation the last step in recovering all the products is to acidify the acid salt to retrieve the the carboxylic acid. We do this by adding dilute HCL. Sodium Ethanoate + HCL = Ethanoic Acid + NaCl (salt) Na(+) + OOCCH + H(+) + Cl(-) = HOOCCH + NaCl (All are aqueous) Finally we would use distillation to separate the Ethanoic acid from the NaCl.