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STOCKTON CHEM 2140 - Kinetics

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Chapter 13: KineticsHomework Problems:1) Express the rate of reaction2HI(g)  H2(g) + I2(g)a) in terms of [H2]b) in terms of [HI]2) For the reaction5Br-(aq) + BrO3(aq) + 6H+(aq)  3Br2(aq) + 3H2Oit was found that at a particular instant bromine was being formed at the rate of 0.039 mol/L s. At that instant,at what rate was the water being formed? at what rate was the bromine ion being oxidized? at what rate was H+ being consumed?3) Dinitrogen pentaoxide decomposes according to the following equation:2N2O5(g)  4NO2(g) + O2(g)a) write an expression for reaction rate in terms of [ N2O5]b) write an expression for reaction rate in terms of [NO2]c) write an expression for reaction rate in terms of [O2]4) What is the order with respect to each reactant and the overall order of the reactions described by the following rate expressions?a) rate = k[A]3 b) rate = k[A][B] c) rate = k[A][B]2 d) rate = k[B]e) rate = kChapter 1315) Complete the following table for the reaction, which is first order in both reactantsA(g) + B(g)  products[A] [B] k (L/mol s) Rate (mol/L s)0.200 0.300 1.50.029 0.78 0.0250.450 0.520 0.0336) The decomposition of ammonia on tungsten at 1100C is zero-order, with a rate constant of 2.5 x 10-4 mol/L mina) Write the rate expressionb) Calculate the rate when the concentration of ammonia is 0.080Mc) At what concentration of ammonia is the rate equal to the rate constant?7) For the reaction involving a single reactant A, the following data are obtainedRate (mol/L min) 0.020 0.016 0.013 0.010[A] 0.100 0.090 0.080 0.070Determine the order of the reactionChapter 1328) In solution at constant H+ concentration, I- reacts with H2O2 to produce I2H+(aq) + I-(aq) + ½ H2O2(aq)  ½ I2(aq) + H2OThe reaction rate can be followed by monitoring iodine production. The following data apply:[I-] [H2O2] Initial rate (mol/L s)0.020 0.020 3.3 x 10-50.040 0.020 6.6 x 10-50.060 0.020 9.9 x 10-50.040 0.040 1.3 x 10-4a) What is the order with respect to I-?b) What is the order with respect to H2O2?c) Calculate the rate constant, kd) What is the rate when [I-] = 0.010M and [H2O2] = 0.030M?9) In the first-order decomposition of acetone at 500 C it is found that the concentration is 0.0300 M after 200 min and 0.0200M after 400 min. H3C-CO-CH3(g)  productsCalculatea) The rate constantb) The half-lifec) The initial concentrationChapter 13310) The decomposition of hydrogen iodide is second-order. Its half-life is 85 seconds when the initial conc. is 0.15MHI(g)  ½ H2(g) + ½ I2(g)a) What is k for the reaction?b) How long will it take to go from 0.500M to 0.200M?11) Write the rate expression for each of the following elementary steps:a) K + HCl  KCl + Hb) NO3 + CO  NO2 + CO2c) 2NO2  2NO + O212) For the reaction2H2(g) + 2NO(g)  N2(g) + 2H2O(g)The experimental rate expression is rate = k[NO]2[H2]The following mechanism is proposed:2NO  N2O2fastN2O2 + H2  H2O + N2O slowN2O + H2  N2 + H2O fastShow that the mechanism is consistent with the rate expression.Chapter 13413) Hydrogen peroxide decomposes to water and oxygen according to thefollowing reactionH2O2(aq)  H2O + ½ O2(g)It’s rate of decomposition is measured by titrating samples of the solution with potassium permanganate (KMnO4) at certain intervals.Initial rate determinations at 40C for the decomposition give the following data:[H2O2] Initial Rate (mol/L min)0.10 1.93 x 10-40.20 3.86 x 10-40.30 5.79 x 10-4a)1) What is the order of the reaction? 2) Write the rate equation for the decomposition. 3) Calculate the rate constant at 40C4) Calculate the half-life for the reaction at 40Cb) Hydrogen peroxide is sold commercially as a 30.0% solution. If the solution is kept at 40C, how long will it take for the solution to become 10.0% H2O2?c) It has been determined that at 50 C, the rate constant for the reaction is 4.32 x 10-3/min. calculate the activation energy for the decomposition of H2O2Chapter 135d) Manufacturers recommend that solutions of hydrogen peroxide be kept in a refrigerator at 4C. How long will it take for a 30.0% solution to decompose to 10.0% if the solution is kept at 4C?e) The rate constant for the uncatalyzed reaction at 25C is 5.21 x 10-4/min. The rate constant for the catalyzed reaction at 25C is 2.95 x 108/min.1) What is the half-life of the uncatalyzed reaction at 25C?2) What is the half-life of the catalyzed reaction?Chapter


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