Lesson 3.3.14

3.3.14 Organic synthesis Quiz: AQA Chemistry, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.3.14, Organic synthesis: 20 multiple choice questions for the AQA Chemistry (7405), Unit 3: Organic chemistry, written with Revision Ninja.

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The 20 questions

  1. Why do chemists aim to design processes that do not require a solvent?

    • Solvents always stop reactions from happening, so they must be removed at once
    • Solvents create waste and can be hazardous, so avoiding them is greener
    • Solvents increase the number of steps needed, which lowers the overall yield
    • Solvents make all products toxic, so they must be replaced with water in every step

  2. Why do chemists aim for production methods with fewer steps?

    • Fewer steps always need toxic reagents, which is why longer routes are preferred
    • Fewer steps prevent any product forming, so more steps are needed to make it
    • Fewer steps usually mean higher overall yield, less waste and lower cost
    • Fewer steps always need more energy, which makes the process more expensive

  3. What is atom economy?

    • Mr of the desired product divided by the sum of Mr of all products, multiplied by 100
    • Mass of reactants divided by mass of solvent, which measures the concentration used
    • Actual yield divided by theoretical yield, multiplied by 100 to give a percentage
    • Number of steps divided by number of atoms, which gives the efficiency of the route

  4. What is the maximum number of steps in a synthesis that students are expected to devise in this specification?

    • Six
    • Four
    • Ten
    • Two

  5. What is the atom economy of the addition of HBr to ethene to form bromoethane?

    • 75%
    • 100%
    • 50%
    • 25%

  6. What is the atom economy of CH3CH2Br + NaOH -> CH3CH2OH + NaBr?

    • 93%
    • 50%
    • 31%
    • 69%

  7. Which reaction type has the highest atom economy in general?

    • Addition
    • Elimination
    • Substitution with a by-product
    • Oxidation with a by-product

  8. Ethene is converted to ethanol and then to ethanoic acid. What is the minimum number of steps from ethene to ethanoic acid?

    • 1
    • 3
    • 2
    • 4

  9. What is the minimum number of steps from ethanol to ethyl ethanoate?

    • 1
    • 2
    • 4
    • 3

  10. What is the overall yield of a three-step synthesis where each step has a yield of 80%?

    • 240%
    • 80%
    • 51.2%
    • 24%

  11. What is the percentage yield definition?

    • Theoretical yield divided by actual yield, multiplied by 100
    • Actual yield divided by theoretical yield, multiplied by 100
    • Mass of solvent divided by mass of product
    • Mr of product divided by Mr of reactants

  12. Which of these explains why atom economy and percentage yield are different measures?

    • They are the same measure calculated in different units, so either one can be used interchangeably
    • Atom economy depends only on the solvent used, while percentage yield depends only on the apparatus
    • Atom economy measures the cost of the reagents used, while yield measures the time taken to complete the reaction
    • Atom economy is a theoretical calculation from equations, while percentage yield compares actual with theoretical mass

  13. Which of the following makes a synthesis route greener?

    • Using large amounts of toxic solvents, which speeds up the reaction and cuts cost
    • Adding extra unnecessary steps, which makes the route more reliable in the lab
    • Choosing reactions with the most by-products, which gives more products to sell
    • Using non-hazardous starting materials and avoiding solvents

  14. What is the advantage of a higher atom economy?

    • It always makes the reaction faster, because more atoms take part in each step
    • It removes the need for purification, because all of the atoms end up in the product
    • It increases the mass of by-product formed, which is then sold as a second product
    • Less waste by-product is produced per unit of desired product

  15. What is the atom economy of the elimination of water from ethanol to form ethene?

    • 100%
    • 50%
    • 61%
    • 39%

  16. Which reaction converts a primary alcohol to an aldehyde, using controlled oxidation?

    • Reduction with NaBH4, which converts the alcohol into an alkane in one step
    • Oxidation with acidified dichromate under distillation
    • Esterification with ethanoic acid, which forms an ester rather than an aldehyde
    • Addition of HBr to an alkene, which forms a halogenoalkane rather than an aldehyde

  17. What is the atom economy of CH3CH2OH + [O] -> CH3CHO + H2O, where ethanal is the desired product?

    • 71%
    • 100%
    • 50%
    • 29%

  18. Methane reacts with chlorine: CH4 + Cl2 -> CH3Cl + HCl. What is the atom economy for CH3Cl?

    • 74%
    • 42%
    • 58%
    • 100%

  19. What determines the overall yield of a multi-step synthesis?

    • The number of solvent molecules used
    • The yield of the first step only
    • The product of the individual step yields
    • The sum of the individual step yields

  20. Which reaction converts a primary alcohol to a carboxylic acid?

    • Reduction with NaBH4, which converts the acid back into the alcohol in one step
    • Addition of HCN, which adds cyanide across a C=O group to give a hydroxynitrile
    • Hydrolysis of an amide with water only, which gives the carboxylic acid and an amine
    • Oxidation with excess acidified dichromate under reflux

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