Alchols

• Who is the presenter of the video on alcohols for the AQA specification?

  Chris Harris
• What is the purpose of the video on alcohols?

  It is a revision video providing a quick overview of the alcohols topic.
• What functional group do all alcohols contain?

  The hydroxy group (–OH).
• What are the three types of alcohols based on their structure?

  • Primary alcohols: One alkyl group attached to the carbon with the –OH group.
  • Secondary alcohols: Two alkyl groups attached to the carbon with the –OH group.
  • Tertiary alcohols: Three alkyl groups attached to the carbon with the –OH group.
• What is an example of a primary alcohol?

  Butan-1-ol.
• What is an example of a secondary alcohol?

  Butan-2-ol.
• What is an example of a tertiary alcohol?

  1. Methylpropan-2-ol.
• Why is it important to distinguish between primary, secondary, and tertiary alcohols?

  They react differently when oxidized.
• What is the process of dehydration of alcohols?

  • Removal of water from alcohols.
  • Produces alkenes.
  • Can be done sustainably using fermentation of glucose from plants.
  • Involves an acid catalyst (sulfuric or phosphoric acid).
• What is the significance of using plant material for making alkenes?

  It is a renewable source compared to crude oil, which is non-renewable.
• What is the reaction called when water is removed from a molecule?

  Dehydration.
• What is the role of an acid catalyst in the dehydration of alcohols?

  It facilitates the reaction by providing H+ ions.
• How does the dehydration mechanism of alcohols involve carbocation intermediates?

  The reaction forms a carbocation intermediate that stabilizes the positive charge during the elimination of water.
• What happens to the carbocation intermediate during the dehydration of alcohols?

  Electrons from a neighboring bond stabilize the carbocation by forming a double bond.
• What is the boiling point of cyclohexanol?

  83°C.
• What are the steps involved in the distillation process for making cyclohexene from cyclohexanol?

  1. Add concentrated sulfuric or phosphoric acid to cyclohexanol in a round bottom flask.
  2. Use anti-bumping granules to ensure smooth boiling.
  3. Heat to 83°C to evaporate components with lower boiling points.
  4. Collect the vapor in a condenser to form liquid cyclohexene.
• What is the purpose of using a separating funnel in the purification of cyclohexene?

  To separate the organic layer (cyclohexene) from the aqueous layer containing impurities.
• What is the role of a drying agent in the purification of cyclohexene?

  To remove any remaining water from the cyclohexene.
• What is the hydration of alkenes process?

  • Adding water to alkenes to produce alcohols.
  • Requires steam and an acid catalyst (phosphoric acid).
  • Involves the formation of a carbocation intermediate.
• What is the product formed from the hydration of ethene?

  Ethanol.
• What is the significance of the H+ ion in the hydration of alkenes?

  It helps to form a bond with the alkene during the reaction.
• How does the mechanism of hydration differ from dehydration in alcohols?

  Hydration involves adding water, while dehydration involves removing water.
• What is the product formed when the bond between hydrogen and oxygen is broken in the reaction described?

  Ethanol (C$_2$H$_5$OH)
• What happens to the hydrogen atom when the bond is broken in the reaction?

  The hydrogen is lost and falls off.
• What does the presence of H⁺ ions at the start and end of the reaction indicate?

  It indicates that the acid has been reformed, proving the role of a catalyst.
• What is fermentation and its significance in alcohol production?

  • A sustainable method for producing alcohol or alkenes.
  • Alternative to ethene and steam for making ethanol.
  • Uses glucose from plants.
  • Involves yeast in anaerobic conditions.
• What is the chemical formula for glucose?

  C$_6$H$_{12}$O$_6$
• What are the products of the fermentation process involving glucose?

  Ethanol and carbon dioxide.
• Why is temperature control important in the fermentation process?

  Enzymes work best at specific temperatures, typically between 30 and 40°C.
• What happens to the rate of reaction when temperatures are too low or too high during fermentation?

  At low temperatures, the reaction is too slow; at high temperatures, enzymes become denatured.
• What is the process of fractional distillation used for in fermentation?

  • To obtain pure alcohol from the fermentation mixture.
  • Involves heating the mixture to separate components based on boiling points.
• What is a biofuel?

  A fuel made from dead biological matter, such as ethanol from sugar cane.
• Why is Brazil significant in the context of biofuels?

  Brazil produces a lot of sugar cane, which is fermented to produce ethanol for fuel.
• What are the advantages and disadvantages of using biofuels like ethanol?

  Advantages:

  • Renewable and sustainable.
  • Carbon neutral due to CO₂ absorption during plant growth.

  
  

  Disadvantages:

  • Expensive to convert engines for higher ethanol levels.
  • Land used for fuel could be used for food production.
• What is the carbon neutrality of biofuels like ethanol?

  While burning ethanol releases CO₂, it is considered nearly carbon neutral because the plants absorb CO₂ during growth.
• What are the exceptions to the carbon neutrality of biofuels?

  Fossil fuels are used for transportation and fertilizers, which contribute to CO₂ emissions.
• What are the oxidation products of alcohols?

  • Primary alcohols can be oxidized to aldehydes and then to carboxylic acids.
  • Secondary alcohols are oxidized to ketones.
  • Tertiary alcohols cannot be oxidized by mild oxidizing agents.
• What is the role of potassium dichromate in alcohol oxidation?

  It is a mild oxidizing agent that changes color from orange to green when reduced.
• How can you distinguish between aldehydes and ketones using Fehling's solution?

  Aldehydes reduce Fehling's solution, changing it from blue to brick red precipitate, while ketones do not react.
• What is the result of using Tollens' reagent with aldehydes and ketones?

  Aldehydes produce a silver mirror effect, while ketones do not react.