OCR A Jan 2012 Paper 5 Q1

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Answer all the questions. 1 A student investigates the reaction between iodine, I2, and propanone, (CH3)2CO, in the presence of aqueous hydrochloric acid, HCl(aq). The results of the investigation are shown below. Rateconcentration graph initial rate /mol dm3 s1 Results of initial rates experiments [I2(aq)] /mol dm3 experiment 1 2 3 [(CH3)2CO(aq)] / mol dm3 1.50103 3.00103 3.00103 [HCl (aq)] / mol dm3 2.00102 2.00102 5.00102 initial rate / mol dm3 s1 2.10109 4.20109 1.05108 (a) Determine the orders with respect to I2, (CH3)2CO and HCl, the rate equation and the rate constant for the reaction. Explain all of your reasoning.OCR 2012<br /> [9] (b) The student then investigates the reaction of hydrogen, H2, and iodine monochloride, ICl. The equation for this reaction is shown below. H2(g) + 2ICl(g) 2HCl(g) + I2(g) The rate equation for this reaction is shown below. rate = k[H2(g)] [ICl(g)] Predict a possible two-step mechanism for this reaction. The first step should be the rate-determining step. step 1step 2[2]OCR 2012 [Total: 11] Turn over<br />

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