A LevelChemistryOCRExam Questions6. Organic Chemistry & Analysis (A Level Only)6.3 Carboxylic Acids & Esters

Carboxylic Acids & Esters (OCR A Level Chemistry)

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6.3 Carboxylic Acids & Esters

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6.3 Carboxylic Acids & Esters

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11 mark

The displayed formula of an organic compound is shown below.

propyl-butanoate

What is the systematic name of this organic compound?

  • Propyl propanoate

  • Propyl butanoate

  • Butyl propanoate

  • Butyl butanoate

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21 mark

Equal amounts of the four compounds are added to the same volume of water.

Which compound would produce the most acidic solution?



  • CH3CONH2

  • CH3COOH

  • CH3COOCH3

  • CH3COCl

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31 mark

Esters can be hydrolysed under acidic or alkaline conditions.

Which statement about the hydrolysis of esters is correct?

  • The alkaline hydrolysis of an ester is a reversible reaction

  • The acid hydrolysis of an ester uses sodium hydroxide under reflux

  • The alkaline hydrolysis of an ester produces the parent carboxylic acid and alcohol

  • The acid hydrolysis of an ester does not go to completion

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41 mark

Organic reactions can be completed by the use of acyl chlorides or acid anhydrides instead of carboxylic acids.

Which reason about the use of acyl chlorides and acid anhydrides is correct?

  • Acyl chlorides are safer and quicker to use than acid anhydrides

  • Acid anhydrides are less reactive than acyl chlorides

  • Acid anhydrides produce strong, corrosive acids as a byproduct of the reaction

  • Acyl chlorides are less expensive than acid anhydrides

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51 mark

Methanoic acid reacts with propanol in the presence of a small amount of concentrated sulphuric acid.

What is the correct name for the ester formed?

  • Methyl propyl sulfate

  • Methyl propanoate

  • Propyl ethanoate

  • Propyl methanoate

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11 mark

Which alcohol could be used to prepare HCOOCH(CH3)2?

  • Propan-1-ol

  • Propan-2-ol

  • 2-Methylpropan-2-ol

  • Methanol

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21 mark

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

ester-e

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

Which of the following compounds could be used to produce ethyl propanoate?

 

(CH3CH2CO)2O

CH3CH2CHO

CH3CH2CH2OH

A

✓

✓

✓

B

✓

✓

x

C

x

✓

✓

D

✓

x

x

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    41 mark

    The structure of the analgesic ibuprofen is shown below:

    ibuprofen-mcq

    Which of the following is not a correct statement about ibuprofen?

    • It will react with alcohols to produce an ester

    • It will react with magnesium oxide to form a salt

    • It will react with sodium carbonate solution

    • It has geometric isomers

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    51 mark

    A student added equal amounts of four compounds to the same volume of water and measured the resulting pH.

    Which compound would have produced the solution with the lowest pH?

    • CH3CH2CONH2

    • CH3CH2COOH

    • CH3CH2COOCH3

    • CH3CH2COCl

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    11 mark

    This question is about triesters with identical alkyl (R) groups. The triester is shown below.

    yABXpgZ5_ocr-a2-6-3h-mcq-q1-triester

    1. A triester has a relative molecular mass, Mr, of = 722 when each of the alkyl (R) groups has the formula CH3(CH2)12.
    2. When completely combusted, one mole of the triester with CH3(CH2)9 alkyl (R) groups reacts with 50 moles of oxygen.
    3. Triesters must be hydrolysed with dilute NaOH at a high temperature so the value of Kc is high. 

    • 1, 2 and 3

    • Only 1 and 2

    • Only 2 and 3

    • Only 1

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    21 mark

    A student investigated the extent to which propyl butanoate was hydrolysed. The carboxylic acid extracted from 3.50 g of propyl butanoate reacted with 23.50 cm3 of 0.20 mol dm-3 sodium hydroxide.

    What percentage of propyl butanoate was hydrolysed?

    • 1.75 %

    • 15.31 %

    • 17.46 %

    • 34.91 %

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    31 mark

    N-(4-hydroxyphenyl)ethanamide is commonly known as paracetamol.

    ocr-a2-6-3h-mcq-q3-paracetamol

    Which statement(s) is/ are correct?

    1. Paracetamol has a relative molecular mass of 151.
    2. An addition-elimination reaction with ethanoic anhydride is preferred to the reaction with ethanoyl chloride because it is less exothermic.
    3. Recrystallisation would require a solvent in which paracetamol dissolves when cold but is insoluble when heated.

    • 1, 2 and 3

    • Only 1 and 2

    • Only 2 and 3

    • Only 1

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    41 mark

    Below is the structure of three molecules, X, Y and Z.

     qAiLuQ1h_ocr-a2-6-3h-mcq-q4-molecules-x-y-z

    Which statement is correct?

    • The IUPAC name for molecule X is methylbutanoate.

    • On addition of NaHCO3, molecule X will effervesce. 

    • In the dissociation reaction of Y, the value of Kc is close to 1. 

    • Molecule Z has a chain isomer that is optically active.

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    51 mark

    Propanoyl chloride takes part in the following reactions:

    • Reaction 1: Propanoyl chloride + methylamine
    • Reaction 2: Propanoyl chloride + methanol

    Which statement(s) is/are correct?

    1. Reaction 1 is a condensation reaction where the methylamine nitrogen lone pair attacks the ?+ carbonyl carbon to produce N-methylpropanamide.
    2. Reaction 2 is an addition-elimination reaction where the carbonyl oxygen lone pair causes a partial positive charge on the carbon atom, making it susceptible to nucleophilic attack. 
    3. Propanoyl chloride is used in reactions 1 and 2 instead of propanoic anhydride because the reactions are quicker, safer and cheaper.

    • 1, 2 and 3

    • Only 1 and 2

    • Only 2 and 3

    • Only 1

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