Organic Part 3 Alcohols

Question 1

4.29C functional group of alcohols

Answer 1

• OH
• group of atoms in a molecule that determines the typical chemical reactions and properties of the group of chemicals that is is found in

Question 2

4.31C how can ethanol be oxidised

Answer 2

Ethanol can undergo oxidation in three different ways:

• combustion
• aerobic oxidation
• treatment with an oxidising agent (potassium dichromate)

Question 3

4.31C combustion

Answer 3

cobalt chloride paper blue -> pink
limewater colourless -> cloudy

ethanol + oxygen -> carbon dioxide and water
C2H6O + O2 -> 2CO2 + H2O

Question 4

4.31C aerobic oxidation

Answer 4

• bacteria in the air uses oxygen from the air to oxidise the ethanol in wine
• ethanol reacts with oxygen in the air to form ethanoic acid
• electrons can be used as an oxidising agent

Question 5

4.31C oxidising agent

Answer 5

• something that removed electrons from a compound (or gives it oxygen)
• an example of this is potassium dichromate(VI)
• add 1cm of potassium dichromate into a boiling tube
• place boiling tube into beaker of boiling water and add 1cm of ethanol
• shake tube

Question 6

• 4.31C Observations of oxidising agent

Answer 6

• potassium dichromate is orange before heating
• green after heating
• vinegar smell

Question 7

4.32C how can ethanol be manufactured

Answer 7

• hydration of ethene

- fermentation

Question 8

4.32C hydration of ethene

Answer 8

• phosphoric acid (catalyst)
• 300 °C
• 60-70 atmospheres pressure
• continuous flow process
• very rapid and efficient
• produces much purer ethanol
• uses finite resources based on crude oil
• C2H4 + H2O -> C2H5OH

Question 9

4.32C fermentation

Answer 9

• sugar in water, yeast (catalyst)
• 30-40 °C
• absence of air
• batch process
• very slow
• produces impure ethanol which then needs further processing
• gentle temperatures and atmospheric pressure
• uses renewable resources based on plant material
• C6H12O6 -> 2C2H5OH + 2CO2