Edexcel Jun 2015 (IAL) Paper 5 Q23

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23 This question is about an unknown organic compound, Q. The percentage composition by mass of Q is carbon = 37.8%; hydrogen = 6.30%; chlorine = 55.9%. (a) Calculate the empirical formula of Q. (2) (b) The mass spectrum of Q is shown below. Relative intensity 100 80 60 40 20 10 20 30 40 50 60 70 80 90 100 110 120 130 140 m/e (i) Use your answer to part (a) and the mass spectrum to deduce the molecular formula of Q. (1)18 *P45074A01828*<br /> (ii) Explain why there are three peaks in the molecular ion region (m/e from 126 to 130) of the mass spectrum of Q. (2)(iii) State why the peak at m/e = 126 is the highest of the three peaks in the molecular ion region. (1)*P45074A01928* 19 Turn over<br /> *(iv) Q reacts with aqueous sodium hydroxide to form an organic compound, R. The functional groups of compound R are on different carbon atoms. Compound R reacted slowly with sodium, producing a total of one mole of hydrogen gas per mole of R. When compound R was heated under reflux with excess acidified sodium dichromate(VI), an organic compound, S, was formed. Compound S reacted rapidly with sodium, producing a total of 0.5 mol of hydrogen gas per mole of S. Draw the displayed formulae of the two possible structures for compound S. Explain how your structures are consistent with these data. (5) Structure I Structure II Explanation20 *P45074A02028*<br /> (v) Compound S reacted with iodine dissolved in aqueous sodium hydroxide, producing a pale yellow precipitate with an antiseptic smell. Identify the pale yellow precipitate and hence identify which of the structures that you have given in (b)(iv) is compound S. Explain your reasoning. (2)(vi) Name compound R and give the equation for its reaction with sodium. (3) R =Equation (Total for Question 23 = 16 marks) TOTAL FOR SECTION B = 50 MARKS *P45074A02128* 21 Turn over<br />

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