CIE Nov 2017 v2 Paper 5 Q2

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PMT Activated charcoal is a form of carbon with a very high surface area. It can be used to remove impurities from mixtures. It does this by a process called adsorption, where particles of the impurity bond (adsorb) to the activated charcoal surface. A student wanted to determine the ability of activated charcoal to adsorb a blue dye (the impurity) from aqueous solution. The equation that links the mass of activated charcoal with the amount of blue dye adsorbed is shown. log D m = A + b log [X] D = difference in concentration of dye (in g dm3) before and after adsorption m = mass of activated charcoal (in g) [X] = final concentration of dye (in g dm3) after adsorption A and b are constants The student used the following procedure to investigate the ability of activated charcoal to adsorb a blue dye from an aqueous solution.Place a 50.0 cm3 sample of a 25.00 g dm3 solution of blue dye in a conical flask. Add a weighed mass of activated charcoal to the flask. Stir the contents of the flask for three minutes and then leave for one hour. Filter the mixture. Determine the final concentration of the blue dye, [X], by colorimetry. Repeat the procedure using different masses of activated charcoal.UCLES 2017 9701/52/O/N/17 [Turn over<br /> (a) The final concentrations of blue dye after carrying out the procedure, [X], are shown in the table. 10 (i) Process the results to complete the table. Record your data to two decimal places. PMT mass of activated charcoal, m / g 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 initial final concentration of blue dye concentration of blue dye, [X] / g dm3 / g dm3 difference in concentration of blue dye, D / g dm3 D m log D m log [X] 25.00 25.00 25.00 25.00 25.00 25.00 25.00 25.00 25.00 0.96 0.69 0.60 0.41 0.33 0.27 0.23 0.20 0.17 120.20 97.24 81.33 70.26 61.68 54.96 49.54 45.09 41.38 2.08 1.99 1.91 1.85 1.79 1.74 1.69 1.65 1.62 [3] (ii) By considering the data in the first three columns, state the effect of increasing the mass of activated charcoal, m, on the amount of adsorption that occurs.Explain this effect.[2]UCLES 2017 9701/52/O/N/17<br /> 11 (b) Plot a graph on the grid to show the relationship between log D m and log [X]. Use a cross () to plot each data point. Draw the straight line of best fit. PMT D mlog 2.15 2.10 2.05 2.00 1.95 1.90 1.85 1.80 1.75 1.70 1.65 1.60 1.55 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 log [X]UCLES 2017 9701/52/O/N/17 [2] [Turn over<br /> PMT (c) Circle the most anomalous point on the graph. 12 Suggest a reason why this anomaly may have occurred during the experimental procedure.[2] (d) (i) Use the graph to determine the gradient of the best-fit line. State the co-ordinates of both points you used in your calculation. Determine the value of the constant b. co-ordinates 1co-ordinates 2gradient =b =[2] (ii) Use the graph to determine a value for A. A =[1] [Total: 12] Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.UCLES 2017 9701/52/O/N/17<br />

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