OCR A Specimen Paper 2 Q20

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30 20 Cyclohexanone can be prepared in the laboratory by reacting cyclohexanol with concentrated sulfuric acid and sodium dichromate. Ethanedioic acid is added to the reaction mixture to react with any excess dichromate. The mixture is then distilled. The impure distillate is a mixture of cyclohexanone and water. You will need to refer to some or all of the following data to answer these questions. Boiling point /C Density /g cm3 Mr 100.0 98.0 Cyclohexanol Cyclohexanone (a)* Draw a labelled diagram to show how you would safely set up apparatus for distillation and describe a method to obtain a pure sample of cyclohexanone from the distillate. 161 156 0.962 0.948 Specimen . . . . . . . . .[6]OCR 2014 H432/02<br /> 31 (b) Ethanedioic acid removes excess dichromate ions, Cr2O7 2, as in the equation below. 3(COOH)2 + Cr2O7 2 + 8H+6CO2 + 2Cr3+ + 7H2O Suggest how you could tell when the excess dichromate has completely reacted with the ethanedioic acid.[1] (c) A student monitors the course of this reaction using thin-layer chromatography (TLC). Outline how TLC could be used to monitor the course of the reaction. . . .[2] (d) Plan an experiment that would allow the student to confirm the identity of the pure organic product by means of a chemical test. Specimen . . . . .[3]OCR 2014 H432/02 Turn over<br />

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