Syllabus Edition

First teaching 2023

First exams 2025

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Esters (CIE AS Chemistry)

Exam Questions

1 hour17 questions
11 mark

Methanoic acid is one of the two reactants used to produce an ester with the molecular formula C5H10O2

How many isomeric esters, including structural isomers and stereoisomers, could be made with this molecular formula?

  • 3

  • 4

  • 5

  • 6

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21 mark

The structure of ester E is shown in the diagram below. 

3-6-e-5

E is hydrolysed in the presence of hydrochloric acid. 

Which are the products of this hydrolysis?

  • CH3CO2H and (CH3)2CHCH2CH2CHO

  • CH3CO2H and (CH3)2CHCH2CH2OH

  • CH3COCl and (CH3)2CHCH2CH2OH

  • CH3CHO and (CH3)2CHCH2CH2OH

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31 mark

The ester in the diagram below has an odour of banana.

3-6-e-6

Which pair of reactants can be used to produce this ester under suitable conditions?

  • 3-6-e-6a

  • 3-6-e-6b

  • 3-6-e-6c

  • 3-6-e-6d

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11 mark

Cetyl palmitate is a waxy solid and has the molecular formula C15H31CO2C16H33.

Which products are formed when cetyl palmitate is heated under reflux with an excess of aqueous sodium hydroxide?

  • C15H31CO2Na and C16H33OH

  • C15H31CO2Na and C16H33ONa

  • C15H31OH and C16H33CO2Na

  • C15H31ONa and C16H33CO2Na

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21 mark

The diagram shows the structure of ethanedioic acid.

3-6-m-5

Ethanedioic acid reacts with ethanol in the presence of a few drops of concentrated sulfuric acid to form a diester. The molecular formula of the diester is C6H10O4.

What is the structural formula of the diester?

  • CH3CH2CO2CO2CH2CH3

  • CH3CH2OCOCO2CH2CH3

  • CH3CH2O2CO2CCH2CH3

  • CH3CO2CH2CH2OCOCH3

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31 mark

Lactic acid is a naturally occurring molecule. 

3-6-m-7

What is a property of lactic acid?

  • It rapidly decolourises aqueous bromine.

  • Two molecules can react together in strong acid.

  • It reduces Fehling’s reagent.

  • It is insoluble in water.

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41 mark

How many ester compounds have the molecular formula C4H8O2?

  • 2

  • 3

  • 4

  • 5

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51 mark

Compound Q has the formula CH3CH2CO2CH3.

What is the name of compound Q and how does its boiling point compare with that of butanoic acid?

 

Name of Q

Boiling point compared to butanoic acid

A

B

C

D

Methyl propanoate

Propyl methanoate

Methyl propanoate

Propyl methanoate

Lower 

Lower

Higher

Higher

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    11 mark

    In the presence of an H+ catalyst, compound X reacts with ethanoic acid to produce the compound below.

    3-6-h-1

    What is the molecular formula of compound X?

    • C4H8O

    • C4H8O2

    • C2H6O2

    • C2H6O3

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    2a1 mark

    During a lesson, a teacher heated ethyl propanoate under reflux with aqueous sodium hydroxide. The two organic products are then separated, purified and weighed.

    Out of the total mass of products obtained, what is the percentage by mass of each product?

    • 50.0 % and 50.0 %

    • 57.7 % and 42.3 %

    • 61.7 % and 38.3 %

    • 67.6 % and 32.4 %

    2b1 mark

    In the presence of an H+ catalyst, compound X reacts with ethanoic acid to produce the compound below.

    3-6-h-1

    What is the molecular formula of compound X?

    • C4H8O

    • C4H8O2

    • C2H6O2

    • C2H6O3

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    3a1 mark

    Use of the Periodic Table is relevant to this question.

    During a lesson, a teacher heated ethyl propanoate under reflux with aqueous sodium hydroxide. The two organic products are then separated, purified and weighed.

    Out of the total mass of products obtained, what is the percentage by mass of each product?

    • 50.0 % and 50.0 %

    • 57.7 % and 42.3 %

    • 61.7 % and 38.3 %

    • 67.6 % and 32.4 %

    3b1 mark

    30 g of an alcohol and 30 g of a carboxylic acid are heated under reflux together to produce 33 g of propyl butanoate.  

    What is the yield of the ester?

    • 25 %

    • 38 %

    • 50 %

    • 66 %

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