Alcohols

Question 1

What is an alcohol?

Answer 1

An organic compound with an -OH group

Question 2

Draw the structure of the first three alcohols

Answer 2

Methanol, ethanol and propanol

Question 3

Name a given alcohol, diol or triol

Answer 3

Methanol, Methan-diol, Methan-triol

Question 4

What are the physical properties of alcohols?

Answer 4

Relatively high mp and bp, miscible with water

Question 5

Explain the physical properties of alcohols

Answer 5

OH group leads to hydrogen bonding

Question 6

What are the two methods for production of ethanol?

Answer 6

Fermentation of glucose, hydration of ethene

Question 7

What are the conditions for the production of ethanol from ethene?

Answer 7

Heat, sulphuric acid catalyst, water

Question 8

What conditions are necessary for the fermentation of glucose?

Answer 8

Compromise temperature of 35°C, enzymes, sealed vessel

Question 9

Give two advantages of production of ethanol from glucose

Answer 9

Low tech required, renewable, potentially carbon neutral

Question 10

Give three disadvantages of production of ethanol from glucose

Answer 10

Slow, Low yield, Significant land use, Has to be distilled, Labour intensive

Question 11

How is ethanol extracted after fermentation of glucose?

Answer 11

Fractional distillation

Question 12

Give two advantages of production of ethanol from ethene

Answer 12

Fast reaction, Pure product, Continuous process, Low on manpower, High yield, 100% alcohol

Question 13

Give three disadvantages of production of ethanol from ethene

Answer 13

High technology, Non-renewable source, Expensive equipment

Question 14

Write a balanced symbol equation for the complete combustion of a given alcohol

Answer 14

CH4 + 2O2 -> CO2 + 2H2O

Question 15

What is a dehydration of an alcohol reaction?

Answer 15

One where water is eliminated from an alcohol

Question 16

What is the product of a dehydration of an alcohol reaction

Answer 16

An alkene

Question 17

What conditions are necessary for dehydration of an alcohol

Answer 17

Conc. phosphoric/sulphuric acid catalyst, heat and reflux

Question 18

What is the advantage of dehydrating alcohols to form alkenes?

Answer 18

Alkenes can be used as chemical feedstock without using crude oil

Question 19

What is an oxidation reaction in organic chemistry?

Answer 19

A reaction where oxygen is added or hydrogen is removed from a compound

Question 20

What can primary alcohols be oxidized to?

Answer 20

Aldehydes and carboxylic acids

Question 21

What can secondary alcohols be oxidized to?

Answer 21

Ketones

Question 22

What can tertiary alcohols be oxidized to?

Answer 22

Nothing

Question 23

How is oxidation symbolized in an equation?

Answer 23

[O]

Question 24

What reagent is used for the oxidation of alcohols?

Answer 24

Acidified potassium dichromate

Question 25

What colour change is observed in the oxidation of alcohols?

Answer 25

Acidified potassium dichromate turns green from orange

Question 26

Which experimental method is used to convert alcohols to carboxylic acids?

Answer 26

Reflux

Question 27

Which experimental method is used to convert alcohols to aldehyde

Answer 27

Distillation

Question 28

Which chemical tests can distinguish between aldehydes and ketones?

Answer 28

Tollens’s reagent or Fehling’s solution

Question 29

What is observed when Tollens’ reagent is added to aldehydes?

Answer 29

Silver mirror

Question 30

What is observed when Fehling’s solution is added to aldehydes?

Answer 30

Orange precipitate