CJC_H2_CHEM_P2_QP Prelim

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2 9647/02/CJC JC2 Preliminary Exam 2014 Planning (P) 1 FA1 is a solution of 1.00 mol dm-3 sodium hydroxide, NaOH. FA2 is a solution of 1.00 mol dm -3 acid which is either a monobasic with the formula HA, or dibasic with the formula H2A. You are required to determine the basicity of an acid (either monobasic or dibasic), based on the information given below and the planning of the procedure you have to undertake. Three separate experiments were carried out. Varying volumes of FA1 were measured and then added to different volumes of FA2 and the rise in temperatures, as a result of the mixing were recorded. The relevant measurements and results are tabulated below. Experiment 1 Experiment 2 Experiment 3 Volume of FA1 / cm3 25 25 50 Volume of FA2 / cm3 25 50 25 Temperature rise, ∆T / oC 6.9 4.6 9.1 (a) (i) Write a balanced equation for the reaction between FA1 and FA2 if the acid is monobasic. Do not omit spectator ions. ………………….…………………………….………………………………………………….. (ii) Write a balanced equation for the reaction between FA1 and FA2 if the acid is dibasic. Do not omit spectator ions. ………………….…………………………….………………………………………………….. [2] (b) You are provided with the following apparatus and materials: 1 thermometer 1 styrofoam cup Two 50 cm 3 measuring cylinders Sufficient FA1 solution Sufficient FA2 solution Plan a simple procedure by describing the steps you would carry out for Experiment 1 given above so as to make the relevant measurements and recordings. You are to use only the apparatus and materials listed above.