AQA Jun 2017 Paper 2 Q5

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10 0 5 Ethanoic acid and ethane-1,2-diol react together to form the diester (C6H10O4) as shown. 2CH3COOH(l) + HOCH2CH2OH(l)C6H10O4(l) + 2H2O(l)0 5 . 1 Draw a structural formula for the diester C6H10O4 [1 mark] 0 5 . 2 A small amount of catalyst was added to a mixture of 0.470 mol of ethanoic acid and 0.205 mol of ethane-1,2-diol. The mixture was left to reach equilibrium at a constant temperature. Complete Table 1. Table 1 Amount in the mixture / mol CH3COOH HOCH2CH2OH C6H10O4 H2O [3 marks] At the start 0.470 0.205 At equilibrium 0.180 Space for working *10* IB/M/Jun17/7405/2<br /> 110 5 . 3 Write an expression for the equilibrium constant, Kc, for the reaction. The total volume of the mixture does not need to be measured to allow a correct value for Kc to be calculated. Justify this statement. [2 marks] Expression Justification 0 5 . 4 A different mixture of ethanoic acid, ethane-1,2-diol and water was prepared and left to reach equilibrium at a different temperature from the experiment in Question 5.2 The amounts present in the new equilibrium mixture are shown in Table 2. Table 2 At new equilibrium Amount in the mixture / mol CH3COOH HOCH2CH2OH C6H10O4 To be calculated 0.264 0.802 H2O 1.15 The value of Kc was 6.45 at this different temperature. Use this value and the data in Table 2 to calculate the amount, in mol, of ethanoic acid present in the new equilibrium mixture. Give your answer to the appropriate number of significant figures. [3 marks] Amount of ethanoic acid *11* mol Turn overIB/M/Jun17/7405/2<br />

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