Rates of Reaction David Martin City and Islington College Students Name: …………………………………………………………………..

Topic Chemistry Aims  This worksheet provides some exercises to help introduce rates of reaction calculations Level Level 2 & Level 3 (16-19 years old) Method PowerPoint slides 3 to 5 questions for the students to answer, slide 7 to 9 answers Hand-Out slides 4 to 5 Equipment  Laptop & Projector  Pens  Hand-Outs Duration Minutes

Rate of Reactions Questions Question 1 The rate equation for the reaction between A and B is: Rate = k[A][B] 2 1) What is the order with respect to A ? _______________ 2) What is the order with respect to B ? _______________ 3) What is the overall order? ________________________ 4) If the concentration of A is doubled, what happens to the rate of the reaction? _______________________________________________ _______________________________________________ 5) If the concentration of B is doubled, what happens to the rate of the reaction? _______________________________________________

Rate of Reactions Questions Question 2 Experiment number Initial concentration of nitrogen monoxide in mol dm -3 Initial concentration of hydrogen in mol dm -3 Initial rate of reaction in mol dm -3 s At 700 o C, nitrogen monoxide and hydrogen react as follows. 2NO(g) + 2H 2 (g) N 2 (g) + 2H 2 O(g) The results of some investigations of the rate of this reaction are shown below. Use the above data to determine the order of the reaction with respect to 1nitrogen monoxide……………………….. 2 hydrogen……………………….. Use these answers to write a rate equation for the reaction. This will include the rate constant, k. ……………………………………………………………………………………………… Determine a value for k, stating the units. k = ………………………………..

Rate of Reactions Questions Question 3 Bromoalkanes react with sodium hydroxide. Use the data below to determine the reaction order of each reactant. ExperimentInitial concentration of (CH 3 ) 3 CBr in mol dm -3 Initial concentration of sodium hydroxide (NaOH) in mol dm -3 Initial rate mol dm -3 s x x x x a) From the above results deduce the order with respect to sodium hydroxide. b) From the above results deduce the order with respect to haloalkane. c) Give the rate equation for the reaction. ………………………………………………………………………………………… Calculate the value of the rate constant and give the units of the rate constant.

Rate of Reactions ANSWERS

Rate of Reactions Questions Question 1 The rate equation for the reaction between A and B is: Rate = k[A][B] 2 1) What is the order with respect to A ? 1 2) What is the order with respect to B ? 2 3) What is the overall order? 3 4) If the concentration of A is doubled, what happens to the rate of the reaction? The rate would double – x 2 5) If the concentration of B is doubled, what happens to the rate of the reaction? The rate would quadruple – x 4

Rate of Reactions Questions Question 2 Experiment number Initial concentration of nitrogen monoxide in mol dm -3 Initial concentration of hydrogen in mol dm -3 Initial rate of reaction in mol dm -3 s At 700 o C, nitrogen monoxide and hydrogen react as follows. 2NO(g) + 2H 2 (g) N 2 (g) + 2H 2 O(g) The results of some investigations of the rate of this reaction are shown below. Use the above data to determine the order of the reaction with respect to 1nitrogen monoxide 2 2 hydrogen 1 Use these answers to write a rate equation for the reaction. This will include the rate constant, k. Rate = k[NO] 2 [H 2 ] Determine a value for k, stating the units. k = Rate [NO] 2 [H 2 ] k =k = 69,444 mol -2 dm 6 s -1

Rate of Reactions Questions Question 3 Bromoalkanes react with sodium hydroxide. Use the data below to determine the reaction order of each reactant. ExperimentInitial concentration of (CH 3 ) 3 CBr in mol dm -3 Initial concentration of sodium hydroxide (NaOH) in mol dm -3 Initial rate mol dm -3 s x x x x a) From the above results deduce the order with respect to sodium hydroxide. 0 b) From the above results deduce the order with respect to haloalkane. 1 c) Give the rate equation for the reaction. Rate = k [(CH 3 ) 3 CBr] Calculate the value of the rate constant and give the units of the rate constant. k = Rate___ [(CH 3 ) 3 CBr] k = 0.12 s -1

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