Lesson 6.2.5

6.2.5 Organic synthesis Quiz: OCR Chemistry, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 6.2.5, Organic synthesis: 20 multiple choice questions for the OCR Chemistry (H432), Unit 5: Organic chemistry and analysis, written with Revision Ninja.

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The 20 questions

  1. Which piece of apparatus is fitted vertically above the flask when heating under reflux?

    • Liebig condenser
    • Buchner funnel
    • Separating funnel
    • Fractionating column

  2. What is the main purpose of heating an organic reaction mixture under reflux?

    • Prevent reagent loss
    • Increase product yield
    • Speed up filtration
    • Remove solvent completely

  3. Which technique is used to rapidly separate solid crystals from a liquid under reduced pressure?

    • Buchner filtration
    • Gravity filtration
    • Fractional distillation
    • Simple distillation

  4. In recrystallisation, how should the impure solid initially be dissolved?

    • Minimum cold solvent
    • Minimum hot solvent
    • Excess hot solvent
    • Excess cold solvent

  5. Why do small quantities of soluble impurities remain in solution during cooling in recrystallisation?

    • High melting point
    • Low concentration
    • Insoluble nature
    • High density

  6. How does the melting point of an impure solid compare to a pure sample?

    • Higher and broader
    • Lower and broader
    • Higher and sharper
    • Lower and sharper

  7. A synthesized solid melts over 128–130 °C, but the pure literature value is 132 °C. Why?

    • Product fully decomposed
    • Product absorbed solvent
    • Product lost carbon
    • Product contains impurities

  8. Which acid catalyst is mixed with concentrated nitric acid to nitrate benzene?

    • Concentrated sulfuric acid
    • Concentrated hydrochloric acid
    • Concentrated ethanoic acid
    • Dilute sulfuric acid

  9. Which reagents convert nitrobenzene into phenylamine in a two-stage reduction?

    • LiAlH4 and ether
    • Tin and HCl
    • NaBH4 and ethanol
    • Hydrogen and nickel

  10. Which compound reacts with ethanoic acid in the presence of acid to form ethyl ethanoate?

    • Ethane
    • Chloroethane
    • Ethanol
    • Ethanal

  11. Which reagents convert propanoic acid into N-methylpropanamide in a two-step synthesis?

    • NaOH then CH3NH2
    • NaBH4 then CH3NH2
    • SOCl2 then CH3NH2
    • SOCl2 then NH3

  12. Which sequence of reagents converts bromomethane into ethylamine in two steps?

    • NH3 then H2/Ni
    • KCN then H2/Ni
    • KCN then NaBH4
    • HNO3 then H2/Ni

  13. Which molecule contains both an amine and a carboxylic acid group?

    • An amino acid
    • An ester
    • An acyl chloride
    • A nitrile

  14. Which functional group identification is correct for a molecule with an -OH group on an aromatic ring?

    • An amide group
    • An ester group
    • A carboxylic acid group
    • A phenol group

  15. Ethanol and ethanoic acid (0.20 mol each) are converted into ethyl ethanoate, Mr 88, in a 60 per cent yield. What is the actual mass of ester obtained?

    • 10.6 g
    • 8.8 g
    • 17.6 g
    • 5.3 g

  16. A student makes 0.12 mol of ethyl ethanoate from a route with a 60 per cent overall yield. What was the theoretical number of moles?

    • 0.12 mol
    • 0.30 mol
    • 0.20 mol
    • 0.072 mol

  17. What property is assessed by comparing a solid product's melting point to literature values?

    • Molar mass
    • Solubility
    • Purity
    • Yield

  18. Which technique is required to oxidise propan-1-ol fully to propanoic acid using acidified dichromate?

    • Distillation
    • Cold room temperature
    • Heating under reflux
    • Reflux with NaBH4

  19. Which reaction forms a new carbon–carbon bond in organic synthesis?

    • Nitration of benzene
    • Ester hydrolysis
    • Friedel–Crafts alkylation
    • Reduction of aldehydes

  20. Why is an aldehyde distilled off immediately during the oxidation of a primary alcohol?

    • To increase yield
    • To prevent reduction
    • To neutralise acid
    • To prevent oxidation

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