RVHS H2 Chem 2012 Prelim P2 QP

CANDIDATE NAME CLASS CENTRE NUMBER RIVER VALLEY HIGH SCHOOL YEAR 6 PRELIMINARY EXAMINATION 6 S INDEX NUMBER H2 CHEMISTRY 9647/02 Paper 2 Structured Questions 11 September 2012 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, class, Centre number and index number 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 staples, paper clips, highlighters, glue or correction fluid. Answer all questions in the space provided. A Data Booklet is provided. Do NOT write anything on it. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Paper 2 Question 1 2 3 4 5 6 7 8 TotalNumber Marks 12 7 7 6 10 9 13 8 72 Paper 1 40 Paper 3 80 Total 192 ____________________________________________________________________________ This document consists of 17 printed pages and 1 blank page. River Valley High School 9647/02/PRELIM/12 [Turn over Preliminary Examination 2012

River Valley High School 9647/02/PRELIM/12 [Turn over Preliminary Examination 2012 2 1 Planning (P) Calcium salts are used in many industrial processes. Calcium oxide is used in the production of cement while calcium nitrate is sometimes used to accelerate the setting of concrete. Calcium oxide is a white hygroscopic solid. Calcium oxide can react with water and as such can cause severe irritation when in contact with skin, eyes or if inhaled. Calcium nitrate is a lso a white hygroscopic solid. Calcium nitrate decomposes on heating to form the oxide, nitrogen dioxide and oxygen. (a) Write a balanced equation, including state symbols, for the thermal decomposition of calcium nitrate. …………………………………………………………………........ ............. [1] (b) Calculate the change in mass of the solid you would expect if 1.00 mol of calcium nitrate underwent thermal decomposition. [1] (c) A container of calcium nitrate was contaminated with calcium oxide. Design an experiment to determine the percentage purity of calcium nitrate by a gravimetric method. You are provided with about 2 g of the impure calcium nitrate. (In gravimetric methods, the object ive is to fo rm a thermally stable solid so that the mass can be determined accurately for analysis.) Your plan should include the following: · A full description of the procedure. · Details of how you would calculate the percentage purity from the measurements made. [Mr of Ca(NO3)2 = 164] …………………………………………………………………........ .............. …………………………………………………………………........ .............. …………………………………………………………………........ .............. …………………………………………………………………........ .............. …………………………………………………………………........ .............. …………………………………………………………………........ ..............