Edexcel Jan 2015 (IAL) Paper 2 Q20

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20 Alcohols, such as ethanol, undergo a number of reactions. (a) Write the balanced equation for the oxidation of ethanol to ethanoic acid. Use displayed formulae to show all the bonds in the reactants and products. Use the symbol, [O], to represent an oxygen atom from the oxidizing agent. State symbols are not required. (3) (b) Ethanol can be oxidized to the aldehyde, ethanal, using the apparatus shown below. water out heat water in (i) State the class of alcohols that can be oxidized to aldehydes. (1)14 *P45042A01424*<br /> (ii) Explain fully why ethanal, rather than ethanoic acid, is produced and collected when the apparatus in (b) is used. (3)(iii) State the purpose of the part of the apparatus labelled A. (1)(c) (i) The distillation product, ethanal, is dried. What test could you use to show that the dry sample is contaminated by ethanol or ethanoic acid? Suggest one reagent that could be used to test for both ethanol and ethanoic acid in the presence of ethanal. Give the observation that would be seen if either were present. (2) ReagentObservation(ii) Physical methods can also be used to identify molecules. Give the formula of a fragment that produces a peak in the mass spectrum of ethanal but not in the mass spectrum of ethanol. Identify one feature in the infrared spectrum of ethanal that distinguishes it from ethanol. Wavenumber values are not required. Mass spectrum fragment(2) Infrared spectrum feature*P45042A01524* 15 Turn over<br /> (d) Ethanol is a highly flammable liquid. However, some other larger and more complex alcohols can be more difficult to burn. One such example is propane-1,2,3-triol, commonly called glycerol, which has the formula CH2OHCHOHCH2OH or C3H8O3. (i) Write the equation for the complete combustion of propane-1,2,3-triol, using its molecular formula. State symbols are not required. C3H8O3 + (cid:111) (ii) Write a possible equation for the combustion of propane-1,2,3-triol in a limited supply of oxygen. Suggest a likely observation of this reaction under these conditions. State symbols are not required. C3H8O3 + (cid:111) (1) (3) Observation16 *P45042A01624*<br /> (e) Halogenoalkanes react with aqueous hydroxide ions to form the corresponding alcohol. (i) Name the type of reaction and mechanism. (2)(ii) Choose a halogenoalkane that will react in this way to form ethanol. Draw the mechanism for this reaction, using appropriate curly arrows. Show clearly any dipoles present and the lone pair of electrons involved in the mechanism. (3) (Total for Question 20 = 21 marks) TOTAL FOR SECTION B = 37 MARKS *P45042A01724* 17 Turn over<br />

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