IJC_H2_CHEM_P1_worked_solution

INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION 2 in preparation for General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Data Booklet Multiple Choice Answer Sheet 9647/01 30 August 2016 1 hour READ THESE INSTRUCTIONS FIRST Write your name and class on all the work you hand in. Write in soft pencil. Do not use staples, paper clips, highlighters, 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. This document consists of 16 printed pages and 0 blank page. Innova Junior College [Turn over

2  IJC 2016 Prelim 2/9647/01 [Turn over Section A For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Carbon disulfide, CS2, is a volatile liquid used in the production of cellophane which is used for food packaging. On combustion, CS2 is oxidised as follows. CS2(g) + 3O2(g) CO2(g) + 2SO2(g) A 20 cm3 sample of carbon disulfide vapour is ignited with 100 cm3 of oxygen. The final volume of gas after burning is treated with an excess of aqueous alkali. Which percentage of this final volume dissolves in alkali? (All volumes are measured at room temperature of pressure.) A 20% B 40% C 60% D 80% Answer: C 1 mole of CS2 reacts with 60cm3 of O2, remaining volume of O2 = 40 cm3 produces 1 mole of CO2 20 cm3 of CS2 produces 20 cm3 of CO2 and 40 cm3 of SO2 Total volume of gases at the end of reaction = 40 + 20 + 40 = 100 cm3 Both CO2 and SO2 are acidic gases which will react with NaOH Hence % of final volume dissolved in alkali 60/100 x 100% = 60% 2 Consider the following half-equations C2O42– 2CO2 + 2e– Fe2+ Fe3+ + e– MnO4– + 8H+ + 5e– Mn2+ + 4H2O What volume of 0.01 mol dm–3 potassium manganate(VII) is needed to completely oxidise 25.0 cm3 of an acidified solution of 0.01 mol dm–3 FeC2O4? A 5 cm3 B 7.5 cm3 C 10 cm3 D 15 cm3 Answer: D Combining eqns: FeC2O4 Fe3++ 2CO2 + 3e– x5

3  IJC 2016 Prelim 2/9647/01 [Turn over MnO4– + 8H+ + 5e– Mn2+ + 4H2O x3 Overall equation: 3MnO4–