1. 1
   A food scientist analyses a bottle of vinegar and confirms it is an aqueous solution containing a carboxylic acid.

   (a)

   Which functional group defines a carboxylic acid?

   [1 mark]

   • A-OH
   • B-COOH
   • C-COO-
   • D>C=C<

   (b)

   Which carboxylic acid is present in vinegar?

   [1 mark]

   • AMethanoic acid
   • BButanoic acid
   • CPropanoic acid
   • DEthanoic acid

   (c)

   Draw out, in words, the structural formula of ethanoic acid, describing how the carbon, hydrogen and oxygen atoms are arranged.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student adds a small piece of magnesium ribbon to a test tube of dilute ethanoic acid. Bubbles of gas are produced immediately.

   (a)

   What gas is produced in this reaction?

   [1 mark]

   • AOxygen
   • BCarbon dioxide
   • CHydrogen
   • DChlorine

   (b)

   The student then adds a spatula of sodium carbonate powder to a fresh sample of the same dilute ethanoic acid. What gas is produced in this second reaction?

   [1 mark]

   • ACarbon dioxide
   • BOxygen
   • CHydrogen
   • DNitrogen

   (c)

   Write a word equation for the reaction between magnesium and ethanoic acid, and name the salt formed.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A cleaning products company is comparing the strength of ethanoic acid with hydrochloric acid at the same concentration, testing both against magnesium ribbon. They observe that the hydrochloric acid reacts much more vigorously than the ethanoic acid.

   (a)

   Suggest, in terms of unbranched-chain carboxylic acid structure, why carboxylic acids such as ethanoic acid generally react less vigorously than strong mineral acids.

   [3 marks]

   (b)

   Describe how the company could test whether a carboxylic acid such as ethanoic acid also reacts with a metal carbonate, and predict the observations they would expect to see.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A chemistry teacher wants to demonstrate the reactions of unbranched-chain carboxylic acids to a class, using ethanoic acid as the example.

   (a)

   Describe the reactions of ethanoic acid with a reactive metal and with a metal carbonate, including word equations, and explain why these reactions confirm that ethanoic acid behaves as a typical acid despite being a weak acid.

   [6 marks]

   (b)

   Evaluate the claim that 'all carboxylic acids react identically regardless of chain length', using unbranched-chain carboxylic acids with up to four carbon atoms as examples, and discuss what structural feature they all share that accounts for their similar chemical behaviour.

   [6 marks]

   Total for question 4: 12 marks

End of questions