CIE A Level Chemistry

Topic Questions

A LevelChemistryCIETopic Questions7. Organic Chemistry (A Level Only)7.5 Carboxylic Acids & Derivatives (A Level Only)

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First teaching 2020

Last exams 2024

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7.5 Carboxylic Acids & Derivatives (A Level Only)

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Medium
1a1 mark

This question is about derivatives of carboxylic acids.

Fig 1.1 shows the structure of a carboxylic acid derivative.

 

butanoyl-chloride

Fig 1.1

State the name of the carboxylic acid derivative in Fig 1.1.

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1b2 marks

Ethanoyl chloride reacts with ethanol to form ethyl ethanoate as shown in Fig 1.2.

formation-of-ethyl-ethanoate-from-ethanoyl-chloride
Fig 1.2

i)
Name the other product formed in this reaction.
[1]
ii)
This reaction can be described as an esterification reaction or an acylation reaction.

   Explain why this reaction can also be described as a condensation reaction.

 [1]

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1c1 mark

Ethanoyl chloride can also react with ammonia to form ethanamide. 

Write an equation for this reaction. 

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1d1 mark

During the preparation of propanoyl chloride, SO2 and HCl were also produced. 

Name the two reactants used to form propanoyl chloride. 

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2a1 mark

Benzoic acid can be formed from the oxidation of methylbenzene. 

Draw the displayed formula of benzoic acid.

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2b5 marks
i)
State the reagents and conditions needed to oxidise methylbenzene to benzoic acid. 

[3]

ii)
Give two observations that could be made during this reaction.

[2]

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2c1 mark

Write an equation to show that benzoic acid acts as a weak acid. 

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3a1 mark

Propanoyl chloride is used for the synthesis of other organic compounds. 

Draw the skeletal formula for propanoyl chloride. 

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3b3 marks
i)
Name the two products formed when propanoyl chloride undergoes hydrolysis.
[2]
ii)
Name the mechanism by which hydrolysis occurs. 
[1]

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3c2 marks

Explain why propanoyl chloride will more readily undergo hydrolysis compared to 2-chloropropane.

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1a2 marks

Acyl chlorides are commonly used carboxylic acid derivatives. 

Ethanoyl chloride reacts with an excess of ammonia. 

A student proposes the following equation to represent the reaction:

CH3COCl + NH3  →  CH3CONH2 + HCl

Correct and explain the student's error.

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1b3 marks

N-methylethanamide can also be formed from ethanoyl chloride. 

i)
Draw the skeletal formula of N-methylethanamide.

[1]

ii)
Write an equation for the formation of N-methylethanamide from ethanoyl chloride. 

[2]

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1c1 mark

Ethanoyl chloride will react with 2-methylpropan-1-ol to form an ester. 

Draw the structure of the ester formed.

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2a1 mark

Esters can be formed from carboxylic acids and acyl chlorides.

Write an equation for the formation of the ester formed from methanol and propanoic acid.

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2b2 marks

Propanoyl chloride can be prepared from propanoic acid. 

i)
Write an equation for the preparation of propanoyl chloride from propanoic acid and phosphorus(V) chloride. 

[1]

ii)
Give one observation of this reaction. 

[1]

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2c5 marks

Name and outline a mechanism for the reaction between methanol and propanoyl chloride to form methyl propanoate.

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2d2 marks

Describe two advantages of using propanoyl chloride over propanoic acid in the preparation of esters in industry.

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3a3 marks

Benzoic acid can be formed from methylbenzene. 

This process occurs in two stages. 

methylbenzene       rightwards arrow with Step space 1 on top   potassium benzoate    rightwards arrow with Step space 2 on top  benzoic acid        

 

i)
Draw the displayed formula for methylbenzene.
[1]
ii)
Draw the displayed formula for benzoic acid.
[1]

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3b3 marks
i)
Name the reaction that takes place in step 1.  
[1]
ii)
Describe the conditions and reagents needed for step 1 and 2 of this reaction.

Step 1: ..........................
Step 2: ..........................
[2]

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3c2 marks

Describe the observations that could be made during step 1.

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3d3 marks

Describe and explain the relative acidities of benzoic acid and phenol. 

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4a3 marks

This question is about butanoyl chloride. 

Butanoyl chloride can be produced from butanoic acid. 

i)
Draw the displayed formula of butanoyl chloride. 
[1]
ii)
Give the name and formula of a reagent that produces butanoic acid from butanoyl chloride. 

[2]

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4b3 marks
i)
Explain why butanoic acid is a weaker acid than 2-chlorobutanoic acid.

[2]

ii)
Draw the skeletal formula for 2-chlorobutanoic acid.

[1]

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4c1 mark

Name a chloro-substituted butanoic acid that is a strong acid than 2-chlorobutanoic acid. 

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4d4 marks

Butanoyl chloride can undergo hydrolysis. 

Outline a mechanism for the hydrolysis of butanoyl chloride. 

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4e5 marks

Explain the relative ease of hydrolysis for butanoyl chloride, chlorobenzene and 1-chorobutane. 

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5a2 marks

Methanoic acid, HCO2H, has a similar acid strength to propanoic acid.

Describe a chemical test to distinguish between these two acids. Name the acid which gives a positive result in this test and describe the observations that would be made.

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5b3 marks

The ester phenyl propanoate, C2H5CO2C6H5, can be made from phenol and propanoic acid in a two step synthesis.

The first step produces an acyl chloride.

For this two step synthesis,

  • draw the structure of the product of the first step
  • state the reagents and conditions needed for each step of the synthesis

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5c1 mark

Explain why an acyl chloride should be formed first for the reaction in part (b).

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