17.7 The Alcohols

Question 1

What is their functional group?

Answer 1

OH

Question 2

As the number of Carbon atoms increase, what happens to the boiling points?

Answer 2

Increases

Question 3

What is their homologous series?

Answer 3

CnH2n+1OH

Question 4

Why is ethanol called a good solvent?

Answer 4

Because it dissolves many substances that do not dissolve in water

Question 5

What is the property that makes ethanol a food solvent for use in glues, printing inks, perfumes, and aftershave?

Answer 5

It is volatile

It evaporates easily.

Question 6

Why is ethanol used as a fuel?

Answer 6

It burns readily in oxygen and gives out a lot of energy.

Question 7

What is ethanol made of in the biological way , fermentation?

Answer 7

It is made of Glucose (a sugar)
And yeast
In the absence of air
(Anaerobic reaction)

Question 8

Why is yeast used in fermination?

Answer 8

It contains enzymes that catalyse the reaction of termination

Question 9

Is fermentation exo or endothermic?

Answer 9

Exothermic as it gives out energy with the alcohol and CO2 being produced.

Question 10

What can break down into glucose, to be used in the reaction of fermentation?

Answer 10

Sugars, starch, Cellulose can break down to glucose so

Maize, sugarcane, potato and wood can make ethanol

Question 11

When does the yeast stop working in the reaction of fermentation?

Answer 11

When the % of ethanol reaches a certain level or when the mixture gets to warm

Question 12

How is the ethanol separated from the final mixture in fermentation?

Answer 12

By fractional distillation

Question 13

What is the other way, other than fermentation, to produce ethanol?

Answer 13

By hydration ( chemical way)
Adding water

Question 14

Hydration to produce ethanol Is EthENE and water, what are the controls needed?

Answer 14

570 degree
60-70 atms pressure
Catalyst phosphoric acid

Question 15

What type of reaction is the hydration of an AlkENE?

Answer 15

It is exothermic and reversible

Question 16

High pressure and low temperature give the best yield in hydration of the AlkENE, Ethene. What is the temperature this reaction is carried out at?

Answer 16

570 degrees

Question 17

What are the advantages of fermentation over hydration to obtain ethanol?

Answer 17

It uses renewable resources

You can use waste plant material

Question 18

Disadvantage of fermentation?

Answer 18

A lot of plaint material is needed so a lot of land is needed.

Fermentation is slow, must start anew for each Batch.

Yeast stops to work at a certain % even if there is glucose left

You need heat for fractional distillation = money

Question 19

Advantages of Hydration

Answer 19

Reaction is fast

Can be run continuously if the ethanol is removed whenever full

Give pure ethanol no need for fractional distillation

Question 20

Disadvantages of hydration

Answer 20

Ethene is made form oil= not renewable resources which means it may run out

A lot of heat = money

Reversible reaction and 570 degrees doesn’t produce a high yield so the unreacted ethENE and steam.

Question 21

What is the reaction of ethanol in oxygen?

Answer 21

C2H5OH + 3O2 -> 2CO2 + 3 H2O + heat (energy)

Question 22

Why is ethanol used as a fuel more often now?

Answer 22

It is cheap

Many counties have no petroleum so it would be better to make ethanol than to imports petroleum

Can fight global warming, since many plants must be grown for ethanol to be produce although when it burns it also produces the greenhouse gas, CO2