AQA A-Level› Organic Chemistry› 3.3.9 Carboxylic Acids & Derivatives› Flashcards
3.3.9

Flashcards

Interactive study deck for carboxylic acids, esters, and acyl chlorides.

Carboxylic Acids & Derivatives: read all 19 questions and answers
  1. What causes the solubility of short-chain carboxylic acids in water?
    Hydrogen bonding between the polar carboxyl group (-COOH) and water molecules.
  2. Explain the trend in solubility of carboxylic acids as carbon chain length increases.
    Solubility decreases because the non-polar, hydrophobic hydrocarbon chain becomes larger, disrupting the hydrogen bonding network of water.
  3. Write the balanced chemical equation for the reaction of ethanoic acid with sodium carbonate.
    2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂
  4. What observation confirms the reaction of a carboxylic acid with sodium hydrogencarbonate?
    Effervescence (bubbles of carbon dioxide gas which turn limewater cloudy).
  5. What are the required reagents and conditions for esterification?
    Carboxylic acid, alcohol, heated under reflux with a concentrated strong acid catalyst (usually concentrated H₂SO₄).
  6. Write the equation for the esterification reaction between methanol and propanoic acid.
    CH₃OH + CH₃CH₂COOH ⇌ CH₃CH₂COOCH₃ + H₂O
  7. State the general functional group formula of an ester.
    RCOOR' (where R and R' are alkyl groups).
  8. Give two common commercial uses of esters.
    Solvents, plasticisers, perfumes, or food flavourings.
  9. What are the products of the acid-catalysed hydrolysis of an ester?
    A carboxylic acid and an alcohol. The reaction is reversible and does not go to completion.
  10. What are the products of the base hydrolysis of an ester using hot aqueous sodium hydroxide?
    A sodium carboxylate salt and an alcohol. This reaction is non-reversible and goes to completion.
  11. What is the chemical structure of a triglyceride?
    A triester made from one molecule of propane-1,2,3-triol (glycerol) and three molecules of fatty acids (long-chain carboxylic acids).
  12. Define transesterification in the context of biodiesel production.
    The reaction of a triglyceride (fat or oil) with methanol or ethanol to produce biodiesel (methyl or ethyl esters) and glycerol.
  13. What catalyst and conditions are used for the commercial production of biodiesel?
    A strong alkaline catalyst (such as NaOH or KOH) under warm/gentle heating conditions.
  14. What is the IUPAC name for glycerol?
    Propane-1,2,3-triol
  15. Why are acyl chlorides much more reactive than carboxylic acids?
    The carbonyl carbon is bonded to two highly electronegative atoms (O and Cl), making it highly electron-deficient (delta positive) and highly susceptible to nucleophilic attack.
  16. What mechanism occurs when acyl chlorides react with nucleophiles?
    Nucleophilic addition-elimination.
  17. What organic product is formed when an acyl chloride reacts with ammonia?
    A primary amide (RCONH₂).
  18. Compare the reaction speed and byproducts of acyl chlorides vs acid anhydrides.
    Acyl chlorides react vigorously at room temperature producing toxic, acidic HCl gas. Acid anhydrides react more slowly and produce non-toxic ethanoic acid.
  19. Why is ethanoic anhydride preferred over ethanoyl chloride in the industrial manufacture of aspirin?
    It is cheaper, less corrosive, less vulnerable to hydrolysis, and does not produce toxic hydrogen chloride (HCl) gas.
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