AP Chemistry Chapter 14 Jeopardy Jennie L. Borders

Round 1 – Chapter 14

100 200 300 400 500 Rate Laws Half-Life Graphing Activation Energy Mechanisms Activation Energy Surprise 100 200 300 400 500

Determine the rate law for the reaction. Rate Laws 100 The reaction 2ClO2 + 2OH-  ClO3- + ClO2- + H2O was studied with the following results: Determine the rate law for the reaction. Experiment [ClO2] (M) [OH-] (M) Rate (M/s) 1 0.060 0.030 0.0248 2 0.020 0.00276 3 0.090 0.00828 Rate = k[ClO2]2[OH-]

Calculate the rate constant. Rate Laws 200 The reaction 2ClO2 + 2OH-  ClO3- + ClO2- + H2O was studied with the following results: Calculate the rate constant. Experiment [ClO2] (M) [OH-] (M) Rate (M/s) 1 0.060 0.030 0.0248 2 0.020 0.00276 3 0.090 0.00828 229.63 M-2s-1

Calculate the rate when [ClO2] = 0.1M and [OH-] = 0.05M. Rate Laws 300 The reaction 2ClO2 + 2OH-  ClO3- + ClO2- + H2O was studied with the following results: Calculate the rate when [ClO2] = 0.1M and [OH-] = 0.05M. Experiment [ClO2] (M) [OH-] (M) Rate (M/s) 1 0.060 0.030 0.0248 2 0.020 0.00276 3 0.090 0.00828 0.115 M/s

Rate Laws 400 Rate = k[BF3][NH3] The following data was measured for the reaction BF3 + NH3  F3BNH3 What is the rate law for the reaction? Experiment [BF3] (M) [NH3] (M) Initial Rate (M/s) 1 0.250 0.2130 2 0.125 0.1065 3 0.200 0.100 0.0682 4 0.350 0.1193 5 0.175 0.0596 Rate = k[BF3][NH3]

Rate Laws 500 The following data was measured for the reaction BF3 + NH3  F3BNH3 What is the rate when [BF3] = 0.100M and [NH3] = 0.500M? Experiment [BF3] (M) [NH3] (M) Initial Rate (M/s) 1 0.250 0.2130 2 0.125 0.1065 3 0.200 0.100 0.0682 4 0.350 0.1193 5 0.175 0.0596 0.1704 M/s

Half-Life 100 How do the half-lives of first-order and second-order reactions differ? Since the half-lives of first-order reactions are not based on initial concentration, then all the half-lives are equal. Since the half-lives of second-order reactions are based on initial concentrations, then each half-life is longer than the previous one.

Half-Life 200 The gas-phase decomposition of SO2Cl2, SO2Cl2  SO2 + Cl2, is first order in SO2Cl2. At 320oC the rate constant is 2.2 x 10-5 s-1. What is the half-life at this temperature? 31,500s

Half-Life 300 Molecular iodine, I2(g), dissociates into iodine atoms at 625K with a first-order rate constant of 0.271 s-1. What is the half-life of the reaction? 2.56s

Half-Life 400 Molecular iodine, I2(g), dissociates into iodine atoms at 625K with a first-order rate constant of 0.271s-1. If you start with 0.050M I2 at this temperature, how much will remain after 5.12s assuming that the iodine atoms do not recombine to form I2? 0.012M

Half-Life 500 The first-order rate constant for the decomposition of N2O5, 2N2O5  4NO2 + O2, at 70oC is 6.28 x 10-3 s-1. What is the half-life of N2O5 at 70oC? 110.35s

Graphing 100 For a second-order reaction, what quantity, when graphed versus time, will yield a straight line? 1/[A]

Graphing 200 Consider the following data: Determine whether the reaction is first order or second order. Time (s) 40 80 120 160 Moles of A 0.100 0.067 0.045 0.030 0.020 First Order

Graphing 300 The gas-phase decomposition of NO2, 2NO2  2NO + O2 is studied at 383oC, given the following data: Is the reaction first order or second order with respect to the concentration of NO2? Time (s) 0.0 5.0 10.0 15.0 20.0 [NO2] (M) 0.100 0.017 0.009 0.0062 0.0047 Second Order

Graphing 400 At 23oC and in 0.5M HCl, the following data was obtained for the disappearance of sucrose: Is the reaction first order or second order with respect to [C12H22O11]? Time (min) 39 80 140 210 [C12H22O11] (M) 0.316 0.274 0.238 0.190 0.146 First Order

Is the following reaction first or second order? Graphing 500 Is the following reaction first or second order? Second Order

Mechanisms 100 The decomposition of hydrogen peroxide is catalyzed by iodide ion. The catalyzed reaction is thought to proceed by a two-step mechanism: H2O2 + I-  H2O + IO- (slow) IO- + H2O2  H2O + O2 + I- (fast) Write the chemical equation for the overall process. 2H2O2  2H2O + O2

Mechanisms 200 Rate = k[H2O2] The decomposition of hydrogen peroxide is catalyzed by iodide ion. The catalyzed reaction is thought to proceed by a two-step mechanism: H2O2 + I-  H2O + IO- (slow) IO- + H2O2  H2O + O2 + I- (fast) Predict the rate law for the overall process. Rate = k[H2O2]

Mechanisms 300 The first step is rate determining. You find the reaction 4HBr + O2  2H2O + 2Br2 to be first order with respect to HBr and first order with respect to O2. You propose the following mechanism: HBr + O2  HOOBr HOOBr + HBr  2HOBr HOBr + HBr  H2O + Br2 Based of the rate law which step is rate determining? Rate = k[HBr][O2] The first step is rate determining.

The second step is slow (rate determining) and the first step is fast. Mechanisms 400 The following mechanism has been proposed for the reaction of NO with H2 to form N2O and H2O: NO + NO  N2O2 N2O2 +H2  N2O + H2O The observed rate law is rate = k[NO]2[H2]. What can we conclude about the relative speeds of the first and second reactions? The second step is slow (rate determining) and the first step is fast.

What is the overall reaction and list any catalysts or intermediates? Mechanisms 500 Ozone in the upper atmosphere can be destroyed by the following two-step mechanism: Cl + O3  ClO + O2 ClO + O  Cl + O2 What is the overall reaction and list any catalysts or intermediates? O3 + O  2O2 Catalyst – Cl Intermediate - ClO

What is the activation energy? The difference in energy between the energy to the transition state and the energy of the reactants.

Activation Energy 200 47,041.61 J/mol The rate of the reaction CH3COOC2H5 + OH-  CH3COO- + C2H5OH Was measured at several temperatures, and the following data was collected: Temperature (oC) k(M-1s-1) 15 0.0521 25 0.101 35 0.184 45 0.332 Determine this data, determine Ea. 47,041.61 J/mol

Activation Energy 300 133,803.44 J/mol The temperature dependence of the rate constant for the reaction is tabulated as follows: Temperature (K) k (M-1s-1) 600 0.028 650 0.22 700 1.3 750 6.0 800 23 Calculate Ea. 133,803.44 J/mol

Activation Energy 400 What part of the energy profile of a reaction is affected by a catalyst? Activation energy

Activation Energy 500 The oxidation of SO2 to SO3 is catalyzed by NO2. The reaction proceeds as follows: NO2 + SO2  NO + SO3 2NO + O2  2NO2 Why do we consider NO2 a catalyst and not an intermediate in this reaction? NO2 is present at the beginning and end of the reaction. Intermediates are formed during the reaction and used during the reaction.

Concentration of reactants Surprise 100 What are the 4 factors that affect the rate of a reaction? Concentration of reactants 2. Catalysts 3. State of reactants 4. Temperature

Surprise 200 The rate doubles. The decomposition of N2O5 in carbon tetrachloride proceeds as follows: 2N2O5  4NO2 + O2. The rate law is first order in N2O5. At 64oC the rate constant is 4.82 x 10-3s-1. What happens to the rate when the concentration of N2O5 is doubled? The rate doubles.

Surprise 300 Consider the hypothetical reaction between A, B, and C that is first order in A, zero order in B, and second order in C. How does the rate change when [A] is doubled and the other reactant concentrations are held constant? The rate doubles.

The rate remains the same. Surprise 400 Consider the hypothetical reaction between A, B, and C that is first order in A, zero order in B, and second order in C. How does the rate change when [B] is tripled and the other reactant concentrations are held constant? The rate remains the same.

The rate increases 27 fold. Surprise 500 Consider the hypothetical reaction between A, B, and C that is first order in A, zero order in B, and second order in C. By what factor does the rate change when the concentrations of all three reactants are tripled? The rate increases 27 fold.