4(e) Alcohols

Question 1

General Formula

Answer 1

CnH2n+1 + OH

Question 2

Functional Group

Answer 2

-OH
(covalently bonded to a carbon chain)

Question 3

Ways in which ethanol can be oxidised

Answer 3

• burning in air or oxygen (complete combustion)
• reaction with oxygen in the air to form ethanoic acid
  (microbial oxidation)
• heating with potassium dichromate(VI) in dilute sulfuric acid to form ethanoic acid

Question 4

Combustion of Ethanol

Answer 4

Ethanol + Oxygen -> Carbon Dioxide + Water

Question 5

Microbial Oxidation of Ethanol

Answer 5

Oxidation of ethanol in air in the presence of microbes (yeast or bacteria)

ethanol + oxygen -> ethanoic acid
C2H5OH + O2 -> CH3COOH

Question 6

Heating with potassium dichromate(VI) in dilute sulfuric acid to form ethanoic acid

Answer 6

Oxidising agent: potassium dichromate
Sulfuric acid (needed for it to act as an oxidising agent)

Heat (goes from orange -> green) Green = Chromate ions

Ethanol + oxidising agent -> ethanoic acid + Water

Question 7

Ways to produce ethanol

Answer 7

• Fermentation
• Hydration of ethene

Question 8

Production of Ethanol: By fermentation

Answer 8

Yeast is added to sugar solution and:
left in a warm place (for optimum performance of enzymes)
in the absence of air (anaerobic respiration)

Glucose -> ethanol + carbon dioxide

Question 9

Production of ethanol: Hydration of ethene

Answer 9

Ethene + Steam -> Ethanol

Question 10

Conditions of production of ethanol: hydration of ethene

Answer 10

Temperature: 300
Pressure: 60-70
Catalyst: Phosphoric Acid