NJC_H1_CHEM_P2_answers

1 NATIONAL JUNIOR COLLEGE SH2 PRELIMINARY EXAMINATION Higher 1 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 2 Structured Questions Answer Section A on the Question Paper. Additional Materials: Data Booklet 8872/02 Friday 28 Aug 2015 2 hours READ THE INSTRUCTIONS FIRST Write your subject class, registration number and name on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use paper clips, highlighters, glue or correction fluid. Section A Answers all questions. Section B Answer two questions on separate answer paper. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use A1 A2 A3 A4 B5 B6 B7 Total This document consists of 13 printed pages and 0 blank page.

2 Section A Answer all questions in this section in the spaces provided. 1 Menthol is an important compound extracted from the peppermint plant. It has important uses in flavouring. The structure of a derivative of menthol is shown below. COOH OH CH3CH3 CH3 (a) Name two other functional groups, other than the carboxylic acid, that are present in the above structure. 2° alcohol, alkene [1] (b) State the type of reaction that occurs, if any, and d raw the structure of the organic products, when the above compound is added to the following reagents. Reagent and conditions Structure of organic product(s), if any (i) Acidified KMnO4, heat COOH O CH3CH3 CH3 HO O O Type of reaction: oxidation (ii) H2, Pt COOH OH CH3CH3 CH3 Type of reaction: reduction (iii) CH3CO2H, conc. H2SO4, reflux COOH O CH3CH3 CH3 C O CH3 Type of reaction: condensation [6] [Total: 7] For Examiner’s use

3 2 (a) Sodium, magnesium and phosphorus are all elements in Period 3 of the Periodic Table. What will you see when these elements are burned separately in excess oxygen? Give an equation, with state symbols, for each reaction. [4] 2Na(s) + ½ O2(g) → Na2O(s) Sodium burns with a bright yellow flame. 2Mg(s) + O2(g) → 2MgO(s) Magnesium burns with a brilliant white flame. P4(s) + 5O2(g) → P4O10(s) Phosphorus burns with a white flame. [1 mark each colour, any wrong equation minus ½ mark] (b) On the axes below, sketch a graph to illustrate the variation of ionic radius of the elements sodium to chlorine. Explain the shape of your sketch. Across each isoelectroni