CJC H2 Chem 2012 Prelim P2 QP

CATHOLIC JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATIONS Higher 2 CANDIDATE NAME CLASS 2T CHEMISTRY 9647/02 Paper 2 Structured Questions Tuesday 21 August 2012 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name and class in the boxes provided above. Write in dark blue or black pen on both sides of the paper. [PILOT FRIXION ERASABLE PENS ARE NOT ALLOWED] You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. Write your answers in the space provided. A Data Booklet is provided. You are reminded of the need for good English and clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part of the question. For Examiner’s Use Paper 1 / 40 Q 1 / 12 Paper 2 Q 2 /13 Q 3 /21 Q 4 /12 Q 5 /14 / 72 Q 1 /20 Q 2 /20 Paper 3 Q 3 /20 Q 4 /20 Q 5 /20 / 80 Total / 192 This document consists of 17 printed pages and 0 blank page. [Turn over

2 9647/02/CJC JC2 Preliminary Exam 2012 Eggshells are rich in calcium carbonate and make good plant fertilisers to replenish calcium, an essential nutrient in plant growth. The eggshells are normally crushed and sprinkled around the plants. The shells will slowly decompose and enrich the soil. The decomposition of CaCO 3(s) may be represented as: CaCO3(s) ® CaO(s) + CO2(g) In the laboratory, all Group II carbonates, MCO3, can be decomposed by heating to give the corresponding oxide, MO, and carbon dioxide, CO2. You are to design an experiment to investigate how the rate of decomposition of Group II carbonates varies down the group. In addition to the standard apparatus available in a school laboratory for gas collection, you are provided with the following materials, · samples of carbonates of magnesium, calcium, strontium and barium, · a stopwatch (a) Briefly describe how you would measure the rate of decomposition of the different carbonates in order to enable comparison. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. …………………………………………………………………………………………………. [1] (b) Draw a diagram of the apparatus and experimental set up that you would use to carry out the experiment. Show clearly the following: · the apparatus used to heat the carbonate, and · how the carbon dioxide will be collected. Label each piece of apparatus used, indicating its size or capacity. [2]

3 9647/02/CJC JC2 Preliminary Exam 2012 [Turn over (c) The temperature of the Bunsen flame varies depending on the ratio of the fuel to oxygen burnt. Besides keeping to the same fuel to oxygen ratio, s uggest how you would control another factor in the heating to ensure a fair comparison of the rate of decomposition of different carbonates. ……………………………………………………………………………………………………. …………………………………………………………