CJC_H1_CHEM_P2_SOL

[Turn over CATHOLIC JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATIONS Higher 1 CANDIDATE NAME CLASS 2T CHEMISTRY 8872/02 Paper 2 Thursday 27 August 2015 2 hours Candidates answer Section A on the Question Paper Additional Materials: Answer Paper Data Booklet Graph Paper (2 sheets) READ THESE INSTRUCTIONS FIRST Write your name and HT group on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all the questions. Section B Answer two questions on separate answer paper. You are advised to spend not more than 1 hour for Section B. You are advised to show all working in calculations. You may use a calculator. The number of marks is given in brackets [ ] at the end of each question or part question. This document consists of 15 printed pages and 1 blank page. For Examiner’s Use Section A A1 /7 A2 /14 A3 /7 A4 /3 A5 /9 Section A 40 Section B B6 /20 B7 /20 B8 /20 Section B 40 P2 Total 80 P1 Total 30 Overall % Grade ANSWERS

2 8872/02/CJC JC2 Preliminary Exam 2015 Section A Answer all questions in this section in the spaces provided. 1 (a) Potassium manganate (VII), KMnO 4, can be reduced by iron ( II) sulfate, FeSO 4. The relevant half-equations for the reaction are given below: MnO4 – + 8H+ + 5e– ⇌ Mn2+ + 4H2O Fe3+ + e– ⇌ Fe2+ Write the balanced equation for the redox reaction which can occur. ……………………………………………………………………………………..…………….... ………………………………………………………………………………………………….... (b) Ketones can be reduced by lithium aluminium hydride, LiA lH4, in dry ether to form secondary alcohols. State another set of reagents and conditions that can also be used for the reduction of ketones. ………………………………………………………………………………………………..….... (c) Ketones are not easily oxidised . However, methyl ketones are a specific class of ketones with the acetyl functional group, RCOCH3, and these can be easily oxidised in the triiodomethane test. State the conditions and reagents necessary for this test and write an equation for the reaction, using RCOCH3. [2] …………………………………………………………………………………………………….. ………………………………………………………………………………………………..….... ………………………………………………………………………………………………..….... (d) Many organic compounds undergo oxidation, albeit to varying degrees. Compare the relative ease of oxidation of benzene and methylbenzene. Write appropriate equations and state reagents and conditions to illustrate your answer. [3] ……………………………………………………………………………………………............ ……………………………………………………………………………………………............ ……………………………………………………………………………………………............ ……………………………………………………………………………………………............ ……………………………………………………………………………………………............ ……………………………………………………………………………………………............ [Total: 7] 8H+ + MnO4 – + 5