18 (2410U20-1) Examiner only 13. (a) In cold weather the wings of an aeroplane can become covered in ice. For safety reasons the wings must be de-iced. The liquid ethane-1,2-diol, CH2OHCH2OH, is used, mixed with water, since this lowers the freezing temperature of water and causes the ice to melt. (i) Use the diagram below to show the intermolecular forces that allow ethane-1,2-diol to dissolve in water. [3] © WJEC CBAC Ltd. 18 (ii) Suggest a reason why the addition of ethane-1,2-diol lowers the freezing temperature of water. [1] C C O H H O H H H H (2410U20-1) Turn over. 19 Examiner only © WJEC CBAC Ltd. 19 (b) Ethane-1,2-diol can be oxidised to ethanedioic acid, (COOH)2. (i) Suggest an oxidising agent suitable to carry out this reaction. [1] .......................................................................................................................................... (ii) Write the equation for this reaction. Use [O] for the oxidising agent. [2] (iii) To ensure complete oxidation the reagents are refluxed. Draw and label the apparatus as it is being used in this reaction. [2] (iv) A sample of the reacting mixture was taken during the reflux process and a mass spectrum was produced. One of the peaks recorded was at m/z 58. Suggest the identity of the molecular ion that gave this peak. [1] ................................................................................... (v) The reaction can be used to prepare a sample of solid ethanedioic acid. This is generally hydrated as (COOH)2.xH2O where x is an integer. 2.00 g of ethane-1,2-diol was oxidised and 3.94 g of hydrated ethanedioic acid was produced. Calculate the relative molecular mass of hydrated ethanedioic acid and hence the value of x in its formula. [4] x = ........................................................ 20 (2410U20-1) Examiner only © WJEC CBAC Ltd. 20 (2410U20-1) Turn over. 21 © WJEC CBAC Ltd. 21 17 Examiner only (vi) I. Complete the equation for the reaction which occurs when ethanedioic acid is heated with excess methanol in acidic conditions. Clearly show the structure of the organic product. [2] COOH COOH 2CH3OH + + II. Name the type of functional group present in the organic product. [1] END OF PAPER 22 (2410U20-1) © WJEC CBAC Ltd. 22 Question number Additional page, if required. Write the question number(s) in the left-hand margin. Examiner only (2410U20-1) 23 © WJEC CBAC Ltd. 23 Question number Additional page, if required. Write the question number(s) in the left-hand margin. Examiner only 24 (2410U20-1) © WJEC CBAC Ltd. 24 BLANK PAGE PLEASE DO NOT WRITE ON THIS PAGE