TJC_H2_CHEM_P1 Prelim

1 2016 TJC H2 Chemistry Preliminary Examination [Turn Over CHEMISTRY 9647/01 Paper 1 Multiple Choice 19th September 2016 1 hour Additional materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. There are forty questions on this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. The use of an approved scientific calculator is expected, where appropriate. This document consists of 18 printed pages. Write your name and Civics Group Write and shade your CG number followed by last 3 digits of NRIC

2 2016 TJC H2 Chemistry Preliminary Examination [Turn Over Section A Part 1 For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 During the bacterial leaching of low grade copper ores, acidified water is sprayed onto the ore chalcopyrite, CuFeS2. Bacteria then convert the insoluble ore into a solution according to the equation shown below: 4CuFeS2 + 17O2 + 4H+ 4Cu2+ + 4Fe3+ + 8SO42- + 2H2O No change occurs in the oxidation state of copper. What changes in oxidation state occur for the iron and the sulfur in this reaction? Change in oxidation state Fe S A +1 +8 B +1 -8 C -1 +6 D -1 -6 2 When cobalt metal is reacted with a solution containing cobalt(III) ions, only cobalt(II) ions are formed. How many moles of Co and Co3+(aq) would result in a mixture containing both cobalt(II) and cobalt(III) ions in the mole ratio of 3:1 after the reaction had taken place? Moles of Co Moles of Co3+ A 1 2 B 1 3 C 1 5 D 2 3 3 Sodium hydrogen carbonate, NaHCO 3, can be prepared from sodium sulfate by a three -step process. Na2SO4(s) + 4C(s)  Na2S(s) + 4CO(g) Na2S(s) + CaCO3(s)  CaS(s) + Na2CO3(s) Na2CO3(s) + H2O(l) + CO2(g)  2NaHCO3(s) What is the mass of sodium hydrogen carbonate (M r = 84.0), to the nearest k g, that could be formed from 100 kg of the sodium sulfate (Mr = 142.1), assuming a 90 % yield in each step? A 43 B 86 C 106 D 118 kg

3 2016 TJC H2 Chemistry Preliminary Examination