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# GCC CHM 152 - Kinetics Worksheet

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Name: __________________________________CHM 152 – Kinetics (Ch. 12) Reaction Rates1. Write the rate expression for the reaction N2 + 3 H2  2 NH32. According to the following unbalanced reaction, if the rate of appearance of oxygen gas is 4.00 x 10-2 M/s, what is the rate of disappearance of KClO3 (g)? KClO3(g)  KCl(g) + O2(g) (high Temp rxn)a. 2.67 x 10-2 M/s b. 6.00 x 10-2 M/s c. 2.00 x 10-2 M/s d. 3.00 x 10-2 M/s e. 5.33 x 10-2 M/s Rate laws3. What is the general rate law for this reaction? H3BO3 + 3 HCl  BCl3 + 3 H2O _________________4. What is the rate law for a zero order overall reaction? ________________5. Name one factor that can increase the success of reactant collisions. Explain how it increases the reaction rate.6. The rate constant for the reaction HNO3 + NH3  NH4NO3 is 14.5 1/M.s If the concentration of nitric acid is 0.050 M and the concentration of ammonia is 0.10 M and both reactants are first order, what will the rate ofthis reaction be?7. The rate law for the following reaction is rate = k[H2][F2]. If the rate is 3.15 x 10-4 M/s when [H2] = 0.084 M and [F2] = 0.25 M, calculate the rate when [H2] = 0.039 M and [F2] = 0.099 M. (Hint: find the rate constantk)Initial Rates / Rate constant (k)8. If the concentration of a reactant is doubled and the corresponding rate quadruples, what is the order with respect to that reactant? __________9. What are the units for the rate constant if the rate law is: rate = k[A][B]2[C]?a. 1/s b. 1/Ms c. 1/M2s d. M/s e. 1/M3sCHM 152 Kinetics Page 1 of 5Name: __________________________________10. When two compounds, A and B, are mixed together, they form compound C, by a reaction that’s not well understood. Fortunately, the following rate information was experimentally determined, as shown below:Experiment [A] (mol/L) [B] (mol/L) Rate (mol/L.sec)1 0.050 0.050 4.0 x 10-32 0.10 0.050 8.0 x 10-33 0.050 0.10 1.6 x 10-2a) Determine the rate law for this reaction.b) Determine the rate constant for this reaction.11. The following data were collected for the reaction of BF3(g) + NH3(g)  F3BNH3(g):Experiment [BF3] (M) [NH3] (M) Rate (M/s)1 0.250 0.250 0.21302 0.250 0.125 0.10653 0.200 0.100 0.06824 0.350 0.100 0.23845 0.175 0.100 0.0596a) What is the overall rate law for this reaction? ___________________________ b) What is the overall order of the reaction? _______________c) What is the value of the rate constant (with correct units)? ___________________________Integrated Rate Laws12. To graphically find the rate constant for a first order reaction you should plot _______ versus time. For a second order reaction? ________ For a zero order reaction? _________CHM 152 Kinetics Page 2 of 5Name: __________________________________Half life13. What percentage of a sample would remain after 8 half lives? ____________________________14. What percentage of a sample remains after 5 half lives? ________________15. What is the half-life for a first order reaction if the initial concentration of reactant is 1.25M and after 69.2 seconds the concentration has dropped to 0.955M? 16. What is the reactant concentration after 78.9 seconds for a second order reaction with a half-life of 3.l0 minutes if the initial concentration was 0.555M?17. A researcher at GCC is running a new chemical reaction that obeys first order kinetics and discovers that after 24 hours only ½ of the reactants are turned into products. How long will it take in hours for 90% of the reactants to be reacted? (Hint: how much is remaining when 90% is reacted?)Mechanisms18. The slow step in a mechanism is also called the ______________________ step.19. If an elementary step has two reactants, what is its molecularity? ______________________20. For this reaction: 2 NO(g) + Cl2(g)  2 NOCl(g) the real rate law is rate = k [NO] [Cl2]If the following steps are the mechanism, which one must be the rate determining step? _________What is the intermediate in this mechanism? _____________ What is the overall order? _______ NO(g) + Cl2(g)  NOCl2(g) step one NO(g) + NOCl2(g)  2NOCl(g) step twoCHM 152 Kinetics Page 3 of 5Name: __________________________________21. For the following reaction, the rate law is found to be Rate = k[Ce4+][Mn2+]. 2 Ce4+ + Tl+  2 Ce3+ + Tl3+ One mechanism for this reaction, containing the following elementary steps, is shown below: 1. Ce4+ + Mn2+ ---> Ce3+ + Mn3+ 2. Ce4+ + Mn3+ ---> Ce3+ + Mn4+ 3. Tl+ + Mn4+ ---> Tl3+ + Mn2+a. There is no catalyst and no intermediate.b. There is no catalyst, but Mn2+ is the intermediate.c. Mn3+ is the catalyst and there is no intermediate.d. Mn2+ is the catalyst and Mn3+ and Mn4+ are the intermediates.e. Mn4+ is the catalyst and Mn2+ and Mn3+ are the intermediates.f. Ce3+ is the catalyst and Tl+ and Mn4+ are the intermediates.22. Which of the following equations represents the rate law for the following elementary process: A + B  C+ D?a. Rate = k[C][D]b. Rate = k[A]c. Rate = k[A][B]2d. Rate = k[A][B]e. Rate = k[B]23. Below is a possible mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. What is the overall reaction equation for this process? H+ + H2O2  H2O+-OH (rapid equilibrium) H2O+-OH + 2Br-  HOBr + H2O (slow) HOBr + H+  Br2 + H2O (fast)a. 2 H+ + H2O2 + Br- + HOBr  H2O+--OH + Br2 + H2 Ob. H2O+--OH + H++ Br-  Br2 + H2Oc. 2 H+ + H2O2 + 2 Br-  Br2 + 2 H2Od. 2 H2O+--OH + 2 Br-  H2O2 + Br2 + 2 H2OArrhenius Equation24. If a reaction has a rate constant of 3.7 x 10-3 s-1 at 25 oC, and an activation energy of 43.6 kJ/mol, what willbe the rate constant for this reaction at 75 oC ?a. 3.0 x 10 -4 s-1b. 4.6 x 10 -2 s-1c. 3.7 x 10 -3 s-1d. 4.8 x 10 -3 s-1CHM 152 Kinetics Page 4 of 5Name: __________________________________25. A second order reaction whose rate constant at 700 oC was found to be 4.0 x 10-3 L/mol.s has an activationenergy of 35.0 kJ/mol. What is the rate constant for this reaction at 850 oC?a. 7.1 x 10-3 L/mol·sb. 5.25 x 10-6 L/mol·sc. 5.78 x 10-2 L/mol·sd. 1.8 x 10-3 L/mol·se. 1.0 x 10-3 L/mol·sCatalysis26. A catalyst increases the rate of a reaction bya. increasing the enthalpy of the reactionb. decreasing the enthalpy of the reactionc. lowering the activation energy of the reactiond. raising the activation energy of the reaction27. A catalyst is effective becausea. it

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