Lesson 18C.2

18C.2 Planning multi-step reaction schemes Quiz: Pearson Edexcel Chemistry, Unit 18

20 questions

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Lesson 18C.2, Planning multi-step reaction schemes: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 18: Organic Chemistry III, written with Revision Ninja.

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The 20 questions

  1. Which reagent converts an alcohol into an alkene by dehydration?

    • Concentrated sulfuric acid, heated, or hot aluminium oxide
    • Lithium tetrahydridoaluminate in dry ether, which reduces the alcohol to an alkane in one step
    • Phosphorus(V) chloride at room temperature, which replaces the hydroxyl group with chlorine gas
    • Dilute sodium hydroxide at room temperature, which removes the hydroxyl group as water in one step
  2. What is the product of heating bromoethane with sodium cyanide in ethanol?

    • Ethanamide
    • Ethanenitrile
    • Butanenitrile
    • Propanenitrile
  3. Ethyl bromide reacts with magnesium in dry ether, then carbon dioxide, then dilute acid. What is the final organic product?

    • Propanoic acid
    • Butanoic acid
    • Ethanoic acid
    • Propan-1-ol
  4. A Grignard reagent reacts with ethanal, followed by aqueous acid. What type of alcohol is formed?

    • A tertiary alcohol
    • A secondary alcohol
    • A primary alcohol
    • A carboxylic acid
  5. A Grignard reagent reacts with propanone, followed by aqueous acid. What type of alcohol is formed?

    • A secondary alcohol
    • A primary alcohol
    • A tertiary alcohol
    • An alkene
  6. What type of alcohol is formed when a Grignard reagent reacts with methanal?

    • A primary alcohol
    • A tertiary alcohol
    • A carboxylic acid
    • A secondary alcohol
  7. Why must Grignard reagents be prepared and used in dry ether?

    • Water would reduce the magnesium so the reagent cannot form
    • Grignard reagents react with water, which would destroy the reagent
    • Dry ether prevents the carbon dioxide from reacting with the reagent
    • Dry ether is needed to dissolve the magnesium metal into solution
  8. Which two-step route converts ethene into ethanoic acid?

    • Oxidation to ethanal, then reduction with lithium tetrahydridoaluminate
    • Hydration to ethanol, then oxidation with acidified dichromate(VI)
    • Bromination to dibromoethane, then hydrolysis to ethanedioic acid
    • Reaction with HCN, then distillation with sodium hydroxide
  9. Which route converts 1-bromopropane into butanoic acid?

    • Reaction with magnesium in ether, then reaction with water only
    • Reaction with KCN, then reduction with lithium tetrahydridoaluminate
    • Reaction with NaOH, then oxidation with dichromate
    • Reaction with KCN, then hydrolysis with dilute acid under reflux
  10. In the preparation of aspirin from salicylic acid, which reagent acetylates the -OH group?

    • Lithium tetrahydridoaluminate, which reduces the carboxyl group
    • Concentrated nitric acid, which nitrates the ring
    • Ethanoic anhydride, which forms an ethanoyl ester
    • Sodium hydroxide, which hydrolyses the -OH group
  11. Why is reflux used when preparing a carboxylic acid by oxidation of an alcohol?

    • It keeps volatile reactants and products in the flask while the mixture is heated for a long time
    • It removes water as it forms to drive an equilibrium, which is needed for every oxidation in the lab
    • It cools the mixture so the product crystallises out during the heating stage of the procedure
    • It separates the product by distilling it as soon as it forms, so the product is removed from the mixture
  12. A synthesis gives 3.5 g of product from a theoretical yield of 6.0 g. What is the percentage yield?

    • 43%
    • 86%
    • 58.3%
    • 70%
  13. Three steps each have a yield of 80%. What is the overall percentage yield?

    • 240%
    • 51.2%
    • 24%
    • 80%
  14. Why is ethanoyl chloride handled in a fume cupboard?

    • It reacts with moisture to release hydrogen chloride, which is toxic and corrosive
    • It forms a toxic cyanide gas on contact with air, which is why it must be kept in a sealed container
    • It is radioactive, so it must be shielded from the operator during the synthesis steps in the lab
    • It is highly flammable and explodes in sunlight, so it must be stored away from any light source
  15. Which reagents convert propanone into 2-methylpropan-2-ol?

    • Lithium tetrahydridoaluminate, followed by heating
    • Sodium hydroxide, followed by heating
    • Methylmagnesium bromide in dry ether, followed by aqueous acid
    • Acidified dichromate(VI), followed by water
  16. Why is steam distillation used for some organic products?

    • To oxidise the product to a carboxylic acid during the distillation, so the final product is an acid
    • To remove all traces of water from the product by heating it with the steam until it is completely dry
    • To distil volatile, water-insoluble compounds at a temperature below their boiling point, reducing decomposition
    • To increase the boiling temperature of the product so that it can be distilled at a higher temperature
  17. Which step forms a new carbon-carbon bond in a synthesis?

    • Hydrolysis of an ester with sodium hydroxide
    • A Grignard reaction with a carbonyl compound or carbon dioxide
    • Reduction of a nitrile with lithium tetrahydridoaluminate
    • Oxidation of a primary alcohol to an aldehyde
  18. Which apparatus is used to heat a reaction for a long period without losing volatile reactants?

    • A simple distillation head with a receiving flask
    • A reflux apparatus with a vertical condenser
    • A separating funnel
    • An open beaker on a hot plate
  19. Calculate the overall percentage yield of a route with two steps giving 75% and 60% yields.

    • 135%
    • 67.5%
    • 15%
    • 45%
  20. What is formed when ethanol is heated under reflux with acidified dichromate(VI)?

    • Ethanal only, which distils off
    • Ethene, which is evolved as a gas
    • Ethyl ethanoate, which forms as the main product
    • Ethanoic acid

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