Alcohols

Cards (46)

  • What is the general formula for alcohols?
    CnH2n+2OC_{n}H_{2n + 2}O
  • The functional group of alcohols is R-OH
  • Alcohols can only be classified as primary, secondary, or tertiary based on their structure.
  • Match the classification of alcohols with their corresponding structure:
    Primary alcohol ↔️ RCH2OHR - CH_{2} - OH
    Secondary alcohol ↔️ RCH(R)OHR - CH(R') - OH
    Tertiary alcohol ↔️ RC(R)(R)OHR - C(R')(R'') - OH
  • What is the IUPAC name for CH3CH2OH?
    Ethanol
  • The IUPAC name for a secondary alcohol with three carbon atoms is propan-2-ol
  • What are structural isomers?
    Same formula, different structure
  • Ethers are functional group isomers of alcohols.
  • Give an example of a functional group isomer of C4H10O.
    1-methoxypropane
  • Alcohols have relatively high melting points and boiling points due to the presence of hydrogen bonds.
  • Arrange the intermolecular forces in order of increasing strength:
    1️⃣ Van der Waals
    2️⃣ Permanent dipole-dipole
    3️⃣ Hydrogen bonds
  • Why does butan-1-ol have a higher boiling point than propan-1-ol?
    Longer carbon chain
  • Alcohols with a low Mr are soluble in water due to hydrogen bonding.
  • What is the reagent used in the hydration of alkenes to produce alcohols?
    Steam
  • The hydration of alkenes requires a phosphoric acid catalyst.
  • Match the alkene with the alcohol produced by hydration:
    Ethene ↔️ Ethanol
    Propene ↔️ Propan-2-ol
    Cyclohexene ↔️ Cyclohexanol
  • What does a curly arrow in a reaction mechanism show?
    Movement of electron pair
  • What are the three important reactions of alcohols?
    Combustion, elimination, oxidation
  • Alcohols burn in oxygen to form carbon dioxide and water.
  • Why do alcohols combust more efficiently than alkanes?
    Presence of an O atom
  • When balancing combustion equations for alcohols, do not forget to include the O in the molecule.
  • Match the alcohol with its balanced combustion equation:
    Ethanol ↔️ C₂H₂OH + 3O₂ → 2CO₂ + 3H₂O
    Cyclohexanol ↔️ C₆H₁₂O + 8½O₂ → 6CO₂ + 6H₂O
    Propane-1,3-diol ↔️ CH₂OHCH₂CH₂OH + 4O₂ → 3CO₂ + 4H₂O
  • Elimination reactions of alcohols form alkenes.
  • What is the key definition of elimination reactions?
    Removal of atoms or groups
  • The elimination reactions of alcohols involve dehydration as water is eliminated
  • What reagent is used in the elimination reactions of alcohols?
    1. H₂SO₄
  • In the elimination reaction of alcohols, the OH group is always removed.
  • Outline the mechanism for the elimination reaction of ethanol:
    1️⃣ Protonation of the OH group to form OH₂⁺
    2️⃣ Loss of water to form a carbocation
    3️⃣ Removal of a proton to form ethene
  • What are but-1-ene and but-2-ene examples of?
    Structural isomers
  • Where are alkenes generally obtained from at present?
    Crude oil
  • In the future, it may become more economical to make ethene from ethanol produced by fermentation
  • Match the current source of ethene with its end product:
    Crude oil ↔️ Poly(ethene)
    Ethanol ↔️ Ethene
  • Alcohols can be oxidised by acidified potassium dichromate(VI).
  • When acidified potassium dichromate(VI) acts as an oxidising agent, its colour changes from orange to green
  • What is the half equation for the reduction of dichromate(VI) ions?
    Cr₂O₇²⁻ + 14H⁺ + 6e⁻ → 2Cr³⁺ + 7H₂O
  • In organic chemistry, what does oxidation involve in terms of bonds?
    Increase in C-O bonds
  • Match the type of alcohol with its oxidation product:
    Primary ↔️ Aldehyde or carboxylic acid
    Secondary ↔️ Ketone
    Tertiary ↔️ No oxidation
  • Acidified dichromate(VI) can distinguish between tertiary alcohols and other alcohols.
  • A primary alcohol is oxidised first to an aldehyde and then to a carboxylic acid.
  • What type of apparatus is essential for producing an aldehyde from a primary alcohol?
    Immediate distillation