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CIE Nov 2014 v3 Paper 4 Q2
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![PMT (a) Bromate(V) ions, BrO3 , react with bromide ions in the presence of acid to produce bromine. Write an ionic equation for this reaction.[2] (b) The initial rate of this reaction was measured, starting with different concentrations of the three reactants. The following results were obtained. experiment number ] [BrO3 / mol dm3 [Br ] / mol dm3 [H+] / mol dm3 initial rate / mol dm3 s1 1 2 3 4 0.040 0.040 0.040 0.080 0.020 0.020 0.080 0.020 0.50 1.00 0.50 0.50 2.64104 1.06103 1.06103 5.21104 (i) Use the data in the table to determine the order with respect to each reactant. Show your reasoning.(ii) Write the rate equation for this reaction.(iii) Use the results of experiment 1 to calculate the rate constant, k, for this reaction. Include the units of k. rate constant, k =units[6] [Total: 8]UCLES 2014 9701/43/O/N/14<br />](https://learnah.org/wp-content/uploads/2018/08/November_2014_v3_QP_-_Paper_4_CIE_Chemistry_A-level_2.jpg)
![Page 3 Mark Scheme Syllabus Paper Cambridge International A LevelOctober/November 2014 9701 43 (ii) Sr(NO3)2 SrO + 2NO2 + 0.5 O2 [2] PMT [3] [2] [6] [4] (d) (down the group) nitrates become more stable / require a higher temperature to decompose as size/radius of ion increases OR charge density of ion decreases so polarisation/distortion of anion/nitrate ion/NO3 /NO bond decreases (a) BrO3 + 5Br + 6H3Br2 + 3H2O five correct species correct balancing st (b) (i) [BrO3 ] 1 order and the concentration is x2, rate doubles OR evidence using expt 1 & 4 eg ratios nd [H ] 2 order and the concentration is x2, rate x4 OR evidence using expt 1 & 2 [Br st - ] 1 order and the concentration is x4, rate x4 OR evidence using expt 1 & 3 eg ratios (ii) (Rate =) k [BrO3 ][Br ][H (iii) k = 1.32 3 1 mol dm (a) (i) chromium and copper (ii) (all orbitals have the) same energy (iii) correct id of one higher energy d orbital the other higher energy d orbitalCambridge International Examinations 2014<br />](https://learnah.org/wp-content/uploads/2018/08/November_2014_v3_MS_-_Paper_4_CIE_Chemistry_A-level_2.jpg)