Alcohols

Question 1

What affects an alcohol’s physical properties?

Answer 1

The ability to form hydrogen bonds between the the OH groups of neighbouring molecules

Question 2

What is volatility?

Answer 2

The ease that a liquid turns into a gas

Question 3

What is the general trend between volatility and boiling point?

Answer 3

Volatility increases as boiling point decreases

Question 4

Why can alcohols dissolve in water?

Answer 4

The OH group can hydrogen bond with water

Question 5

Why does solubility decrease as chain length increases?

Answer 5

A larger part of the alcohol molecule is made up of non polar hydrocarbon chain
The hydrocarbon chain does not form hydrogen bonds with water molecules

Question 6

How do you classify an alcohol?

Answer 6

By looking at the carbon where the functional group is attached to and counting the number of alkyl groups attached to determine whether the alcohol is primary, secondary or tertiary

Question 7

Why does the boiling point increase as chain length increases?

Answer 7

The van der Walls’ forces will increase as chain length increases

Question 8

Why do alcohols have higher boiling points than alkanes?

Answer 8

Alcohols have hydrogen bonding

Question 9

What to draw when drawing hydrogen bonding

Answer 9

Show lone pairs
Show charges
Show hydrogen bond as a line of horizontal lines
Make sure the the O-H-O is drawn at 180 degrees

Question 10

What is required to ensure that complete combustion occurs?

Answer 10

An excess of oxygen

Question 11

How are alcohols oxidised?

Answer 11

An oxidising agent is made from potassium dichromate and sulfuric acid
When an oxidising agent is added to a primary or secondary alcohol, the solution will turn green from orange

Question 12

What is the symbol for an oxidising agent?

Answer 12

[O]

Question 13

What is produced at each stage of oxidation?

Answer 13

Primary -> Water is produced

Secondary -> No water is produced

Question 14

What set up is used for primary oxidation and why?

Answer 14

Simple distillation

Question 15

What is the equation for the fermentation of glucose to make alcohols?

Answer 15

C6H12O6 -> 2CH3CH2OH + 2CO2

Question 16

What is the equation for the direct hydration of ethene

Answer 16

H2C=CH2 +H2O -> CH3CH2OH

Question 17

What are the conditions for the direct hydration of ethene?

Answer 17

The water has to be in the form of steam
Phosphoric acid catalyst
300 degrees
60 atm

Question 18

What are the conditions needed for the ferementation of glucose?

Answer 18

Yeast (zymase)
37 degrees
Absence of air

Question 19

Why does the fermentation process have to be derpived of oxygen?

Answer 19

To prevent the oxidation of ethanol into other products such as ethanal or ethanoic acid

Question 20

Why can ethanol produced by fermentation only be up to 14% alcohol concentration?

Answer 20

The enzyme zymase ceases to function at higher levels of alcohol concentration

Question 21

What percentage of ethene is hydrated at any one time?

Answer 21

5%

Question 22

What happens to the unreacted ethene once it has passed through the reactor?

Answer 22

The gases are recycled and fed back into the system

Question 23

Uses of ethanol

Answer 23

Alcoholic beverages
Perfumes/aftershave
Fuel
Methylated spirits

Question 24

Uses of methanol

Answer 24

Clean burning fuel

Feedstock for the chemical industry

Question 25

What are the four key reactions of alcohols?

Answer 25

Combustion Elimination Oxidation Esterfication

Question 26

What makes ethanol a good fuel?

Answer 26

Renewable source of energy Burns more cleanly Can reduce emissions

Question 27

What are the conditions needed for the dehydration of an alcohol?

Answer 27

Concentrated phosphoric or sulfuric acid | Heated under reflux

Question 28

What is dehydration?

Answer 28

An elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule

Question 29

What is reflux?

Answer 29

The continual boiling and condensing of a reaction mixture to ensure that the reaction takes place without the contents of the flask boiling off

Question 30

What atoms are lost during a dehydration reaction?

Answer 30

The OH group from one carbon atom | An H atom from the adjacent carbon atom

Question 31

What is an elimination reaction?

Answer 31

A reaction where two molecules are made from one molecules

Question 32

When is distillation used?

Answer 32

When oxidising alcohols to form aldehydes The aldehyde would react again to form a carboxylic acid if left in mixture, therefore it must be boilied off to avoid further oxidation

Question 33

What is esterification?

Answer 33

The reaction of an alcohol with a carboxylic acid to produce and ester and water

Question 34

How to name an ester

Answer 34

The alcohol provides the alkyl prefix while the carboxylic acid provides the alkanoate prefix

Question 35

What are the reasgents needed for making an ester?

Answer 35

An alcohol | A carboxylic acid

Question 36

What are the conditions for esterification?

Answer 36

Warmed | Concentrated sulfuric acid to act as a catalyst

Question 37

How to prepare an ester

Answer 37

Add equal amounts of alcohol and carboxylic acid into boiling tube and add conc sufluric acid Place boiling tube in hot water bath for five minutes at 80 degrees Pour product into cold water You will see an oil floating on the water that is the ester

Question 38

What atoms react during esterification to make an ester?

Answer 38

The OH group from the carboxylic acid and the H on the OH group of the alcohol

Question 39

What are esters used for in the chemical industry?

Answer 39

Adhesives Solvents Food fragrances Perfume

Question 40

What is a carbonyl group?

Answer 40

A functional group that consists of a carbon atom double bonded to a oxygen atom