AQA Specimen Paper 3 Q1

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Section A Answer all questions in this section. Ethanol can be oxidised by acidified potassium dichromate(VI) to ethanoic acid in a two-step process. ethanol ethanal ethanoic acid In order to ensure that the oxidation to ethanoic acid is complete, the reaction is carried out under reflux. Describe what happens when a reaction mixture is refluxed and why it is necessary, in this case, for complete oxidation to ethanoic acid. [3 marks] Write a half-equation for the overall oxidation of ethanol into ethanoic acid. [1 mark] . 1 0 1 . 2 0 1 Barcode Typesetter code<br /> . 3 0 1 Barcode The boiling points of the organic compounds in a reaction mixture are shown in Table 1. Table 1 Compound ethanol ethanal ethanoic acid Boiling point / C 78 21 118 Use these data to describe how you would obtain a sample of ethanal from a mixture of these three compounds. Include in your answer a description of the apparatus you would use and how you would minimise the loss of ethanal. Your description of the apparatus can be either a description in words or a labelled sketch. [5 marks] Question 1 continues on the next page Typesetter code Turn over <br /> . 4 0 1 0 1 . 5 Use your knowledge of structure and bonding to explain why it is possible to separate ethanal in this way. [2 marks] A student obtained a sample of a liquid using the apparatus in Question 1.3. Describe how the student could use chemical tests to confirm that the liquid contained ethanal and did not contain ethanoic acid. [5 marks] Barcode Typesetter code<br />

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