EstersIB MYP Chemistry: Subtopic test

1. 1
   A flavour company makes an artificial pineapple flavouring for sweets. The flavouring is an ester, made in the laboratory by heating a carboxylic acid with an alcohol in the presence of a catalyst.

   (a)

   Which functional group is present in every ester?

   [1 mark]

   • A-OH
   • B-COOH
   • C-COO-
   • DC=C

   (b)

   The chemists make the pineapple flavouring from ethanol and butanoic acid. What is the name of the ester formed?

   [1 mark]

   • AButyl ethanoate
   • BEthyl butanoate
   • CButanoic ethyl
   • DEthanoyl butanoate

   (c)

   Outline how the ester is made in the laboratory, naming the catalyst.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student warms ethanoic acid with propan-1-ol and a few drops of concentrated sulfuric acid in a test tube. She pours the mixture into a beaker of cold water and notices a sweet, fruity smell.

   (a)

   What is the name of the ester formed in this reaction?

   [1 mark]

   • AEthyl propanoate
   • BEthyl ethanoate
   • CPropyl propanoate
   • DPropyl ethanoate

   (b)

   Which other product is formed when an ester is made from a carboxylic acid and an alcohol?

   [1 mark]

   • AWater
   • BHydrogen
   • CCarbon dioxide
   • DEthene

   (c)

   State the role of the concentrated sulfuric acid and give one safety precaution the student should take.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Ethyl ethanoate is a colourless liquid used as a solvent in nail varnish remover and in some glues. A factory makes it from ethanoic acid and ethanol.

   (a)

   Write a balanced symbol equation, using molecular or condensed formulae, for the formation of ethyl ethanoate from ethanoic acid and ethanol.

   [3 marks]

   (b)

   Esters are used as solvents, in perfumes and as food flavourings. Explain why esters are suitable for use in perfumes, and describe one other use of esters, with a reason.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A food company makes fruit-flavoured sweets. Its chemists can make esters by heating a carboxylic acid with an alcohol and concentrated sulfuric acid. The company currently buys flavours extracted from real fruit, which are expensive and depend on the size of each year's harvest.

   (a)

   Design an investigation to find out how the choice of alcohol affects the smell of the ester made with ethanoic acid. Use methanol, ethanol, propan-1-ol and butan-1-ol.

   [6 marks]

   (b)

   Discuss and evaluate the company's use of synthetic ester flavourings instead of flavours extracted from real fruit.

   [6 marks]

   Total for question 4: 12 marks

End of questions