Alcohols

Question 1

What is the general formula of the alcohol homologous series?

Answer 1

CnH2n+1 OH

Question 2

What is fermentation?

Answer 2

An exothermic process where glucose is converted to alcohol as a byproduct of anaerobic respiration in yeast.

Question 3

Give the equation for the production of ethanol by fermentation.

Answer 3

C6H12O69(aq) –> 2C2H5OH(g) + 2CO2(g)

Question 4

What are the conditions of the fermentation of alcohols?

Answer 4

Temperature = 35C
Pressure = normal atmospheric pressure
Catalyst = enzyme in yeast (zymase)
Other = aqueous and anaerobic

Question 5

What raw materials are used in the fermentation of alcohols and what are these types?

Answer 5

Carbohydrate crops (e.g. sugar, maize)
They are renewable

Question 6

Fermentation of alcohols - what is this type of process called?

Answer 6

Batch (stop-start)

Question 7

What is the reaction rate of the fermentation of alcohols?

Answer 7

Slow.

Question 8

What is the purity of alcohol in the fermentation of alcohols?

Answer 8

Impure (10%) (must be purified by fractional distillation which is costly)

Question 9

What is the cost of fermentation of alcohols?

Answer 9

Expensive - cheap equipment needed, high labour costs.

Question 10

What is the equation of combustion of ethanol?

Answer 10

C2H5OH + 3O2 + 3H2O

Question 11

How is biofuel produced?

Answer 11

From renewable biological resources

Question 12

Fermentation can occur at 25C. In industry the fermentation reaction is carried out at 35C rather than 25C
a) Suggest one advantage and one disadvantage for industry of carrying out the fermentation at this higher temperature.

Answer 12

Ethanol is produced as a faster rate

However, it is costly to keep the high temperature.

Question 13

b) What does carbon neutral mean?

Answer 13

There is no net release of CO2 into the atmosphere.

Question 14

Is fermentation carbon neutral?

Answer 14

It depends.

Question 15

What happens in the hydration of ethene?

Answer 15

Ethene is mixed with steam and passed over a catalyst consisting of solid silicon coated with phosphoric acid.

Question 16

What is the equation for the hydration of ethene?

Answer 16

CH2 = CH2 +H2O –> C2H5OH

Question 17

What does hydration mean?

Answer 17

The addition of water to a compound.

Question 18

What conditions are needed for the hydration of ethene?

Answer 18

Temperature = 300C
Pressure = 70 atm
Catalyst = concentrated phosphoric acid

Question 19

What raw material are used for the hydration of ethene?

Answer 19

Crude oil

Question 20

What raw material type used for the hydration of ethene?

Answer 20

Finite (non-renewable)

Question 21

What type of process is the hydration of ethene?

Answer 21

Continuous

Question 22

What is the reaction rate of the hydration of ethene?.

Answer 22

Fast

Question 23

What is the purity of ethanol in the hydration of ethene?

Answer 23

Pure.

Question 24

Describe the classification of alcohol

Answer 24

Primary, secondary and tertiary- according to how many other groups (R) are. Bonded to the carbon that has the -OH group.

Question 25

Describe the physical properties of alcohols

Answer 25

The -OH group has hydrogen bonds between molecules which means also alcohols have higher melting points than alkanes of the same relative molecular mass.

Question 26

What are elimination reactions?

Answer 26

Where the small molecule leaves the parent molecules. In alcohols it’s water so the elimination reaction of water is always dehydration

Question 27

Describe the dehydration of alcohols.

Answer 27

Alcohols can be dehydrated with excess hot concentrated sulfuric acid or by passing the vapour over heated aluminium oxide. An alkene is formed.