Alcohols (Chapter 15)

Question 1

How are alcohos named?

Answer 1

-ol (usually after the number where the functional group is) e.g. butan-2-ol

Question 2

What is the general formula for alcohols?

Answer 2

CnH(2n+1)OH

Question 3

What is the prefix for a compound with an alcohol and another functional group?

Answer 3

Hydroxyl

Question 4

Describe and explain the boiling points of alcohols

Answer 4

Relatively high boiling points as they are able to form hydrogen bonds between molecules.

Question 5

Describe and explain the volatility of alcohols

Answer 5

Relatively low vocatively as they are able to form hydrogen bonds between molecules.

Question 6

What is a primary alcohol?

Answer 6

Where one carbon is attached to the carbon adjoining the oxygen.

Question 7

What is a secondary alcohol?

Answer 7

Where 2 carbons are attached to the carbon adjoining the oxygen.

Question 8

What are tertiary alcohols?

Answer 8

Where there are 3 carbons attached to the carbon adjoining the oxygen.

Question 9

What is used as an oxidising agent on alcohols?

Answer 9

Potassium Dichromate (IV) (also need dilute sulphuric acid)

Question 10

What is produced when a primary alcohol is oxidised by distillation?

Answer 10

Aldehyde (+ water)

Question 11

What is the functional group for an aldehyde?

Answer 11

CHO

Question 12

What is the observation when alcohols are oxidised?

Answer 12

Orange dichromate 6+ ion reduces to green Cr3+

Question 13

What are the conditions for oxidation of primary alcohol by distillation?

Answer 13

Warm gently and distil aldehyde as it forms.

Question 14

What is produced when a primary alcohol is oxidised by reflux?

Answer 14

Carboxylic acid

Question 15

What are the conditions for the oxidation of a primary alcohol by reflux?

Answer 15

Use excess of potassium dichromate and heat under reflux (distill off product after reaction has finished)

Question 16

Why are anti-bumping granules?

Answer 16

To prevent vigorous, uneven boiling by making smaller bubbles.

Question 17

What is produced when a secondary alcohol is oxidised?

Answer 17

Ketone

Question 18

What are the condition for the oxidation of a secondary alcohol?

Answer 18

Heat under reflux

Question 19

Why can’t tertiary alcohols be oxidised?

Answer 19

There is no hydrogen atom bonded to the carbon with the OH group.

Question 20

What positive ion does tollens reagent contain?

Answer 20

[Ag(NH3)2]+

Question 21

What are the observation from pollens reagent?

Answer 21

Aldehydes form a coating on the inside of the test tube while ketones have no visible change?

Question 22

What positive ion does Feelings solution contain?

Answer 22

Blue Cu2+

Question 23

Describe the reaction when pollens is added to oxidised alcohols

Answer 23

Only aldehydes are oxidised by tollens to carboxylic acids and silver ions are reduced to silver atoms.

Question 24

What are the conditions for adding tollens reagent to an oxidised alcohol?

Answer 24

Heat gently

Question 25

What are the conditions for adding fehlings solution to oxidised alcohols?

Answer 25

Heat gently

Question 26

What is the observation when feelings reagent is added to oxidised alcohols?

Answer 26

Blue Cu2+ ions are changed to red precipitate of Cu2O

Question 27

Describe the reaction when oxidised alcohols are added to fehlings solution?

Answer 27

Aldehydes are oxidised to carboxylic acids and the Copper (II) ions are reduced to Copper (I)

Question 28

What is produced when an alcohol is dehydrated?

Answer 28

Alkene

Question 29

What are the reagent used to dehydrate an alcohol?

Answer 29

Concentrated sulphuric or phosphoric acid

Question 30

What is the role of the reaction when alcohols are dehydrated?

Answer 30

Dehydrating agent/catalyst

Question 31

What type of reaction is the dehydration of a alcohol?

Answer 31

Acid catalysed elimination

Question 32

Define dehydration?

Answer 32

The removal of a water molecule from a molecule.

Question 33

What are the condition for dehydrating an alcohol?

Answer 33

Warm under reflux

Question 34

What is the equation for the fermentation of glucose?

Answer 34

glucose > ethanol + carbon dioxide C6H12O6 > 2CH3CH2OH + 2CO2

Question 35

What are the conditions for the fermentation of glucose/

Answer 35

* Yeast * No air * Temperatures 30-40ºc

Question 36

Why is 38ºc the optimum temperature for the fermentation of glucose?

Answer 36

At lower the temperature the reaction is too slow. At higher temperature the yeast dies and the enzymes denature.

Question 37

Why is the fermentation of glucose done in the absence of air?

Answer 37

The presence of air can cause other reactions to occur (e.g. it oxidises the ethanol to ethanoic acid)

Question 38

What are the advantages of the fermentation of glucose?

Answer 38

* Sugar is a renewable resource * Production uses low amounts of energy * Cheap equipment

Question 39

What are the disadvantages of the fermentation of glucose?

Answer 39

* Batch process which is slow and gives high production costs * Ethanol is not pure and need to be purified by fractional distillation. * Depletes land use for growing crops.

Question 40

How is ethene produced for the industrial formation of ethanol?

Answer 40

Cracking of fractions from crude oil

Question 41

What is the equation for the production of ethanol form ethene?

Answer 41

Ethene + Water > Ethanol CH2=CH2 (g) + H2O (g) > CH3CH2OH (l)

Question 42

What type of reaction forms ethanol from ethene?

Answer 42

Hydration

Question 43

Define a hydration reaction

Answer 43

Addition of a water molecule to a molecule.

Question 44

What are the condition for producing ethanol from ethene?

Answer 44

* High temperature of 300ºc * High pressure of 70 atm * Strong acidic catalyst of concentrated H3PO4

Question 45

What are the advantages of producing ethanol from ethene?

Answer 45

* Faster reaction * Purer product * Continuous process

Question 46

What are the disadvantages of producing ethanol from ethene?

Answer 46

* High technology equipment needed * Ethene is non-renewable resource * High energy cost to produce high pressure

Question 47

What is a biofuel?

Answer 47

Fuel produced from plants.

Question 48

Define carbon neutral

Answer 48

An activity that has no net annual carbon emission to the atmosphere.

Question 49

How is are carboxylic acids tested for?

Answer 49

Sodium carbonate and it will fizz and produce carbon dioxide.