Ch.13 - Chemical KineticsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Additional Problems
The oxidation of iron (II) ions by iodine in aqueous solution occurs as shown below 2 Fe2+ (aq) + l2 (aq) → 2 Fe3+ (aq) + 2 l - (aq) and the experimental rate law is found to be: Rate = k [Fe2+][I2] The proposed mechanism shown below is a valid choice for this reaction: Fe2+ (aq) + I2 (aq) → Fe3+ (aq) + I2 - (aq) Fe2+ (aq) + I2 - (aq) → Fe3+ (aq) + 2 I - (aq) Which of the following statements is true about the proposed reaction mechanism? a. I2- is the catalyst in this mechanism. b. Fe3+ is the intermediate in this mechanism c. The second step  is the rate determing step. d. The rate determining step is bimolecular e. The reaction is first order overall.    
Choose the INCORRECT statement.       A) The rate-determining step is the slow-step. B) A reaction intermediate is produced and used up during the reaction. C) An activated complex has partially formed bonds. D) the rate of a chemical reaction describes the change in concentration of a reactant or product with time, and may be increased by certain catalytic agents E) The rate of a reaction will be very rapid if the activation energy is large 
Answer the following questions based on the reaction mechanism given. 
When the concentration of A is doubled, the rate for the reaction: 2 A + B → 2 C quadruples. When the concentration of B is doubled the rate remains the same. Which mechanism below is consistent with the experimental observations?        A) Step 1:  A + B → D (slow) Step 2:  A + D → 2 C (fast)        B) Step 1:   A → D (slow) Step 2:  A + B + D → E (fast) Step 3:  E → 2 C (fast)   C) Step 1:  2 A → D (slow) Step 2:  B + D → E (fast) Step 3:  E → 2 C (fast)        D) Step 1:  A + B → D (slow) Step 2:  A + D ⇌ 2 C (fast equilibrium)
Consider the following reaction mechanism Ce4+ (aq) + Mn2+ (aq) ↔ Ce3+(aq) + Mn3+ (aq) Ce4+ (aq) Mn3+ (aq) ↔ Ce3+ (aq) + Mn4+ (aq) Ti+ (aq) + Mn4+ (aq) ↔ TI 3+ (aq) + Mn2+ (aq) Which one of the following species is an  intermediate a. Ce4+ b. TI+ c. Mn2+ d. Mn3+ e. Ce3+
In the reaction demonstrated with the below mechanism, what term best describes I- and IO-: A. Both are intermediates B. Both are catalysts C. I- is a catalyst and IO- is an intermediate D. I- is a reactant and IO- is a catalyst
The Rate law for the reaction 2 NO(g) + Cl2(g) → 2 NOCl(g) is: Rate = k [NO][Cl2] If the following is the mechanism for the reaction                          k1 NO(g) + Cl2(g) → NOCl2(g)                               k2 NOCl2(g) + NO(g) → 2NOCl(g) Which statement is  NOT  true? A) The reaction is 2nd order overall B) k1 < k2 C) Doubling the [Cl2] will double the rate D) The reaction is first order in [Cl2] E) If the volume is doubled the rate will quadruple
Given the following proposed mechanism, predict the rate law for the overall reaction. A2 + 2B → 2AB (overall reaction) Mechanism A2 ⇌ 2A     fast A + B  → AB    slow A. Rate = k[A][B] B. Rate = k[A2][B] C. Rate = k[A2][B]1/2 D. Rate = k[A2] E. Rate = k [A2]1/2[B]
Consider the reaction Cl2 (aq) + H2S (aq) → S (s) + 2 H+ (aq) + 2 Cl - (aq) The rate equation for this reaction is rate = k [Cl2] [H2S] Which of these mechanisms is (or are) consistent with this rate equation? I     Cl2 + H2S → H+ + Cl - + Cl+ + HS -          (slow)       Cl+ + HS - → H+ + Cl - + S                       (fast) II    H2S ⇌ H+ + HS -                                     (fast equilibrium)       Cl2 + HS - → 2Cl - + H+ S                         (slow)   (A) I only (B) II only (C) Both I and II (D) Neither I or II
The decomposition of hydrogen peroxide in the presence of iodide ion is believed to occur via this mechanism.  H2O2(aq) + I - (aq) → H2O(l) + IO - (aq)  H2O2(aq) + IO - (aq) → H2O(l) + O2(g) + I - (aq) In this mechanism, I - (aq) is (A) a catalyst. (B) a reactant in the overall reaction. (C) the activated complex. (D) a product of the overall reaction.
Phosgene is formed by the reaction of Cl 2 and CO. The experimental rate law is  Rate = k [CO][Cl2]3/2. The proposed reaction mechanism is  Cl2(g) ⇌ 2Cl(g)                                       Step 1 Cl(g) + CO(g) ⇌ ClCO(g)                       Step 2 ClCO(g) + Cl2(g) → Cl2CO(g) + Cl(g)     Step 3 For the proposed reaction mechanism to be consistent with the rate law: a) Step 1 is slow and Steps 2 and 3 are fast b) Step 3 is fast and steps 1 and 2 are slow c) Steps 1 and 2 are fast and step 3 is slow d) Steps 1 and 3 are fast and step 2 is slow e) Step 1 is fast and steps 2 and 3 are slow
What is the predicted rate law for the following mechanism? Cl2(g) ⇌ 2Cl(g)                                    Fast Cl(g) + CHCl3(g) → HCl(g) + CCl3(g)  Slow Cl(g) + CCl3(g) → CCl4(g)                   Fast a) Rate = k[Cl2][CHCl3] b) Rate = k[Cl][CCl3] c) Rate = k[Cl][Cl2][CHCl3] d) Rate = k[Cl]1/2[Cl2][CHCl3] e) Rate = k[Cl2]1/2[CHCl3]  
Consider the reaction mechanism  NO2(g) + Cl2(g) → ClNO2(g) + Cl(g)     Slow NO2(g) + Cl → ClNO2(g)                       Fast What is the predicted rate law for this mechanism? a) Rate = k[NO2][Cl2][Cl] b) Rate = k[NO2][Cl] c) Rate = k[NO2]2[Cl2] d) Rate = k[NO2][Cl2] e) Rate = k[NO2]2[Cl2][Cl]−1
1. Sketch the potential energy profile for the mechanism below. 2. Determine the theoretical rate law for this mechanism. Show your work, or explain your reasoning. 3. Is this mechanism consistent with the kinetic data? Explain.    
Consider the following three step reaction mechanism Cl2 (g) →  2 Cl (g) 2 N2O (g) + 2 Cl (g) →  2 N 2 (g) + 2 ClO (g) ClO (g) + ClO (g) →  Cl2 (g) + O2 (g) Which of the following statements are true? 1. N2 is a catalyst. 2. ClO is an intermediate and Cl2 is a catalyst. 3. N2O is a reactant and Cl is a catalyst. 4. N2 is an intermediate and O2 is a final product.
Below is the reaction mechanism for the formation of nitrobenzene: HNO3 + H2SO4 →  H2NO3+ + HSO4- H2NO3+ + C6H6 → C6H6NO2+ + H2O C6H6NO2+ + HSO4-  → H2SO4 + C6H5NO2 Which substance serves as the catalyst? a) H2NO3+ b) HSO4- c) C6H6NO2+ d) H2SO4
The following reaction has a one-step mechanism:  2 A (g) + B (g) → 2 C (g). What is the rate law of the reaction?  
The following reaction has the following rate law: Rate = k[Br2][NO]2 .  2 Br2 (g) + 2 NO (g) → N2 (g) + 2 Br2O (g) The proposed mechanism for the reaction is : Br2 (g) + NO (g) → N (g) + Br 2O (g) [SLOW] N (g) + NO (g) → N2 (g + O (g) [FAST] O (g) + Br2 (g) → Br2O (g) [FAST] Which of the following statements is/are  false? a) The rate determining step is bimolecular. b) There are three elementary steps in the reaction mechanism. c) The mechanism possesses a catalyst. d) O is the only reaction intermediate in this reaction mechanism. e) This not a valid mechanism for the reaction. 
The following reaction in aqueous solution was found to be first order in [OH- ], first order In [C2H5Br], and inverse first order In Br - . C2H5Br + OH - → C2H5OH + Br - Which one of the following mechanisms Is consistent with the observed reaction order? A.) C2H5Br ⇌ C2H5 + + Br - fast  C2H5 + + OH - → C2H5OH slow B.) C2H5Br + H2O → C2H5OH + H+ + Br - slow H+ + OH - → H2O fast C.) C2H5Br ⇌ C2H5 + + Br - slow C2H5 + + OH - → C2H5OH fast D.) C2H5Br ⇌  C2H5 + + Br - slow OH - + Br - → HOBr fast HOBr + C2H5+ → C2H5OH + Br - fast 
The rate law for the reaction 2NO2 + O3 → N2O5 + O2 is rate = K[NO2][O3]. Which one of the following mechanisms Is consistent with this rate law? A. NO2 + NO2 → N2O2 (fast) N2O4 + O3 → N2O5 + O2 (slow) B. NO2 + O3 → NO5 (fast) NO5 + NO5 → N2O5 + (5/2)O2 (slow) C. NO2 + O3 → NO3 + O2 (slow) NO3 + NO2 → N2O5 (fast) D. NO2 + NO2 → N2O2 + O2 (slow) N2O2 + O3 → N2O5 (fast)
Evaluate the plausibility of the following reaction mechanism for: X + 2 Y → 2 Z when the reaction is observed to be second-order with respect to Y but increasing the concentration of X has no effect on the rate. Y + Y → 3 D + E     slow D + X → E               fast D + E → Z               fast D + E → Z               fast a. The mechanism is plausible b. Not plausible as the suggested rate law does not match the observed c. Not plausible as the elementary steps do not equal the overall reaction d. Not plausible as there are more than three elementary steps e. Not plausible as it describes a simultaneous collision of more than three chemicals
Which of the following is a plausible reaction mechanism for 2 H 2 + O2 → 2 H2O, given that the reaction was found to have a rate law of Rate = k [H2] 2? A.) 2 H2 + O2 → 2H2O slow B.) H2 + O2 → 2 OH slow OH + H2 → H2O + H OH + H → H2O C.) H2 + H2 → 4 H slow  2 H + O2 → 2 OH H + OH → H2O H + OH → H2O D.) H2 + H2 → 4 H slow 4 H + O2 → 2 H2O  
Which of the following is a reaction mechanism for A + B → C that shows the presence of a catalyst? A.) D + 2 B → E (slow) A + E → D + C + B (fast)   B.) A → D + B (slow) D + 2 B → C (fast)   C.) A → D + E (slow) D + E + B → C (fast)   D.) 2 B → D (fast) D + A → C + B (slow)   E.) 2 B → 2 D + E (slow) A + 2 D + E → C + B (fast)
Assuming that the following are elementary steps, pick the bimolecular reaction. a) HBr + H2O  → H3O+  +  Br- b) H2O  →  OH-  +  H+ c) A  →  Products d) A  +  B  + C  →  D  
Which rate law is bimolecular? A) rate = k[A][B]3 B) rate = k[A][B] C) rate = k[A]3 D) rate = k[A][B][C][D] E) rate = k[A]2[B]2
Consider the reaction: 2 AB → C2 + 2 BC The following mechanism has been proposed. 2 AB → A2B2                       slow second step                         fast A student is testing this mechanism for plausibility, which of the following statements is/are true? i. the experimental rate law should be Rate = k[AB] 2[C2] ii. the experimental rate law should be Rate = k[AB] 2 iii. A2B2 + C2 → A2 + 2 BC could be fast step a. i only b. ii only c. i and iii d. i and ii e. ii and iii  
Consider the following reaction mechanism for the question: What is the role of H+ in this reaction? (a) reactant (b) catalyst (c) product (d) catalytic intermediate (e) transition state
Consider the following reaction mechanism for the question: What is the role of AcOMeH+ in this reaction? (a) reactant (b) catalyst (c) product (d) catalytic intermediate (e) transition state
Why are termolecular elementary steps rare in gas-phase reactions?
If a molecule like Cl2 falls apart in an elementary reaction, what is the molecularity of the reaction?
What is the difference between a unimolecular and a bimolecular elementary reaction?
Consider the diagram below, which represents two steps in an overall reaction. The red spheres are oxygen, the blue ones nitrogen, and the green ones fluorine. Write the rate law for the overall reaction if the first step is the slow, rate-determining step.
Consider the diagram below, which represents two steps in an overall reaction. The red spheres are oxygen, the blue ones nitrogen, and the green ones fluorine. Write the chemical equation for each step in the reaction.
Consider the diagram below, which represents two steps in an overall reaction. The red spheres are oxygen, the blue ones nitrogen, and the green ones fluorine. Write the equation for the overall reaction.
Consider the diagram below, which represents two steps in an overall reaction. The red spheres are oxygen, the blue ones nitrogen, and the green ones fluorine. Identify the intermediate in the mechanism.
Choose a possible transition state for the bimolecular reaction depicted here . (The blue spheres are nitrogen atoms, and the red ones are oxygen atoms.) The dashed lines is used to represent the bonds that are in the process of being broken or made in the transition state.
The following diagram represents an imaginary two-step mechanism. Let the red spheres represent element A, the green ones element B, and the blue ones element C. Write the equation for the net reaction that is occurring.
The following diagram represents an imaginary two-step mechanism. Let the red spheres represent element A, the green ones element B, and the blue ones element C. Identify the intermediate.
Homogeneous catalysis. Effect of catalyst on the speed of hydrogen peroxide decomposition to water and oxygen gas.Why does the solution in the middle cylinder have a brownish color?
The following diagram represents an imaginary two-step mechanism. Let the red spheres represent element A, the green ones element B, and the blue ones element C. Identify the catalyst.
Can an intermediate appear as a reactant in the first step of a reaction mechanism?
What is an intermediate within a reaction mechanism?
What is meant by the term elementary reaction?
Lock-and-key model for enzyme action.Which molecules must bind more tightly to the active site?
Explain the difference between a normal chemical equation for a chemical reaction and the mechanism of that reaction.
In a reaction mechanism, what is an elementary step? Write down the three most common elementary steps and the corresponding rate law for each one.
What are the two requirements for a proposed mechanism to be valid for a given reaction?
What is a reaction mechanism?
What is meant by the term rate-determining step?
#1 Consider the following mechanism: Step 1: 2A ----> B slow Step 2: B + C ----> D fast Overall 2A + C ----> D Determine the rate law for the overall reaction (where the overall rate constant is represented as k).  #2 Consider the following mechanism: Step 1: 2A <----> B equilibrium Step 2: B + C ----> D slow Overall: 2A + C ----> D Determine the rate law for the overall reaction (where the rate constant is represented as k)
Consider the reaction mechanism given below. Which species is/are intermediates? 1. Cl, ClCO 2. ClCO 3. Pt, ClCO 4. Pt 5. Cl 6. Pt, Cl
Identify the intermediates and catalysts for the reaction mechanism 2X + Y → W + 2Z                     fast W + Z → W + U + V                 slow V + Z → 2W + Y                       fast a) Z is an intermediate and Y is a catalyst b) W and Y are intermediates and there are no catalysts c) Z and Y are intermediates and W is a catalyst d) Z and V are intermediates and Y is a catalyst e) Z and V are intermediates and W is a catalyst
Determine the rate law for the mechanism given below.O3 → O2 + OO + O3 → 2O2 (slow)
Determine the rate law for the mechanism given below.H2 + 2Pd → 2PdHC2H4 + PdH → C2H5Pd (slow)C2H5Pd + PdH → C2H6 + 2Pd 
A reaction mechanism for ozone depletion in the stratosphere is CF3Cl + UV Light → CF3 + Cl Cl + O3 → ClO + O2 O3 + UV light → O 2 + O ClO + O → Cl + O 2 CF3 + Cl → CF3Cl Identify all catalysts and intermediates a) There are no catalysts but CF3, Cl, ClO, and O are intermediates b) UV Light is a catalyst and CF3, Cl, ClO, and O are intermediates c) CF3Cl is a catalyst and CF3, Cl, ClO, and O are intermediates d) O3 is catalyst and CF3Cl, CF3, and Cl are intermediates e) CF3Cl is a catalyst, CF3, Cl, ClO, O, and O2 are intermediates   What is the overall reaction for the mechanism given in the preceding question? a) 2O3 + UV Light → 3O2 b) 2O3 + 2Cl → 2O2 + 2ClO c) O3 + CF3Cl → O2 + ClO + CF3 d) 2O3 + 2ClO + 2CF3 → 3O2 + 2CF3Cl e) O3 + ClO → 2O2 + Cl
The following reaction has a one-step mechanism:2 A (g) + B (g) → 2 C (g).If 10.0 mol of A and 4.0 mol of B are mixed in a 10.0 L container and the rate constant is0.30M -2• s -1 , what is the rate after half of A has been consumed?
Would you expect the following reaction to occur via a one-step mechanism:CH4 (g) + 2O2 (g) → CO2(g) + 2 H2O (l)
The rate law for the reaction H2O2 + 2H+ + 2I - → I 2 +2H2O is rate = k[H2O2][I- ]. The following mechanism has been suggested. H2O2 + I - → HOI + OH-  slow OH- + H+ → H2O fast HOI + H+ + I - → I2 + H2O fast   Identify all intermediates included in this mechanism. A. H+ and I B. H+ and HOI C. HOI and OH D. H+ only E. H2O and OH -
Given the following proposed mechanism, predict the rate law for the overall reaction.2NO2 + Cl2 → 2NO2 Cl (overall reaction) MechanismNO2 + Cl2 → NO2 Cl + Cl              slowNO2 + Cl → NO2 Cl                       fastA) Rate = k[NO 2 ][Cl]B) Rate = k[NO 2 ][Cl 2 ]C) Rate = k[NO 2 Cl] 2D) Rate = k[NO 2 Cl][Cl] 2E) Rate = k[NO 2 ]2 [Cl2 ] 2
A reaction A → D is thought to proceed via the following mechanism:Step 1: A → BStep 2: B → CStep 3: C → D The potential energy profile for the reaction is shown below:Which step is rate-limiting? Identify any intermediate(s). Is the overall reaction endothermic or exothermic?   
Consider the reaction mechanism. Which species would be a catalyst? Step   Reaction                  1           Cl 2 + Pt → 2 Cl + Pt 2           Cl + CO + Pt  → ClCO + Pt 3           Cl + ClCO  → Cl2CO  overall  Cl2 + CO → Cl2CO   1. There are no catalysts in this mechanism 2. Cl 3. Cl2 4. CO 5. ClCO 6. Pt
Indicate whether the following statements are true (T) or false (F):___ The higher the activation energy, the slower a reaction at a given temperature.___ A homogenous catalyst is present in the same phase as the reacting molecules.___ Most reactions occur by a one-step mechanism.___ A unimolecular elementary step involves only a single reactant that breaks apart.___ Termolecular reactions require that three molecules collide simultaneously.___ The half-life of a first-order reaction is constant.___ As the temperature is increased, the number of species reaching the transition state of the rate-determining step increases.
Consider the following mechanism. What species is an intermediate? Which species is a catalyst?Step 1: A + B → ABStep 2: AB + C → AC + BOverall: A + C → AC
What is the molecularity of the elementary reaction: NO(g) + Cl2(g) → NOCl(g) + Cl(g)?
Is each of these statements true? If not, explain why.(p) A bimolecular reaction is generally twice as fast as a unimolecular reaction.
You may want to reference (Pages 593 - 600)Section 14.6 while completing this problem.Consider the following two-step reaction mechanism:A(g) + B(g) → X(g) + Y(g)X(g) + C(g) → Y(g) + Z(g)Which of the following statements about this mechanism is or are true?(i) Both of the steps in this mechanism are bimolecular.(ii) The overall reaction is A(g) + B(g) + C(g) → Y(g) + Z(g).(iii) The substance X(g) is an intermediate in this mechanism.(a) Only one of the statements is true.(b) Statements (i) and (ii) are true.(c) Statements (i) and (iii) are true.(d) Statements (ii) and (iii) are true.(e) All three statements are true.
Is each of these statements true? If not, explain why.(q) The molecularity of an elementary reaction is proportional to the molecular complexity of the reactant(s).
What is the molecularity of each of the following elementary reactions? Write the rate law for the reaction.Cl2 (g) → 2 Cl (g)
What is the molecularity of each of the following elementary reactions? Write the rate law for the reaction.OCl- (aq) + H2O (l) → HOCl (aq) + OH- (aq) 
What is the molecularity of each of the following elementary reactions? Write the rate law for the reaction.NO (g) + Cl2 (g) → NOCl2 (g)
What is the molecularity of each of the following elementary reactions?(a) 2 NO(g) → N2O2(g)
In a hydrocarbon solution, the gold compound (CH3)3AuPH3 decomposes into ethane (C2H6) and a different gold compound, (CH3)AuPH3. The following mechanism has been proposed for the decomposition of (CH3)3AuPH3:Step 1: (CH3)3AuPH3 ⇌ (CH3)3Au + PH3 (fast, k1: forward; k–1: reverse)Step 2: (CH3)3Au → C2H6 + (CH3)Au (slow, k2)Step 3: (CH3)Au + PH3 → (CH3)AuPH3 (fast, k3)What is the molecularity of each of the elementary steps?
Consider this overall reaction, which is experimentally observed to be second order in X and first order in Y: X + Y → XYDoes the reaction occur in a single step in which X and Y collide?
We have seen a number of reactions in which a single reactant forms products. For example, consider the following first-order reaction: CH3NC(g) → CH3CN(g). However, we also learned that gas-phase reactions occur through collisions.One possible explanation is that two molecules of CH3NC collide with each other and form two molecules of the product in a single elementary step. If that were the case, what reaction order would you expect?
The proposed mechanism for a reaction is(1) A(g) + B(g) ⇌ X(g)       [fast](2) X(g) + C(g) ⟶Y(g)      [slow](3) Y(g) ⟶ D(g)                [fast](c) What are the molecularity and the rate law for each step?
Consider the following mechanism:(1) ClO-(aq) + H2O(l) ⇌ HClO(aq) + OH-(aq)         [fast](2) I-(aq) + HClO(aq) ⟶ HIO(aq) + Cl-(aq)           [slow](3) OH-(aq) + HIO(aq) ⟶ H2O(l) + IO-(aq)           [fast](c) What are the molecularity and the rate law for each step?
Why are elementary reactions involving three or more reactants very uncommon?
Define these terms: (a) unimolecular reaction
Define these terms:(b) bimolecular reaction
What is the rate equation for the elementary termolecular reaction A + 2B ⟶ products? For 3A ⟶ products?
Nitrogen(II) oxide, NO, reacts with hydrogen, H2, according to the following equation: 2 NO + 2 H2 ⟶ N2 + 2H2O What would the rate law be if the mechanism for this reaction were: 2 NO + H2 ⟶ N2 + H2O2 (slow) H2O2 + H2 ⟶ 2H2O (fast)
The reaction of CO with Cl2 gives phosgene (COCl2), a nerve gas that was used in World War I. Use the mechanism shown here to complete the following exercises:Cl2 (g) ⇌ 2 Cl (g) (fast, k1 represents the forward rate constant, k−1 the reverse rate constant)CO(g) + Cl(g) ⟶ COCl(g) (slow, k2 the rate constant)COCl(g) + Cl(g) ⟶ COCl2 (g) (fast, k3 the rate constant)(c) Write the rate law for each elementary reaction.
The reaction of CO with Cl2 gives phosgene (COCl2), a nerve gas that was used in World War I. Use the mechanism shown here to complete the following exercises:Cl2 (g) ⇌ 2 Cl (g) (fast, k1 represents the forward rate constant, k−1 the reverse rate constant)CO(g) + Cl(g) ⟶ COCl(g) (slow, k2 the rate constant)COCl(g) + Cl(g) ⟶ COCl2 (g) (fast, k3 the rate constant)(d) Write the overall rate law expression.
Identify the rate law for the reaction 2 NO(g) → N2O2(g)
Identify the rate law for the reaction SO3(g) → SO2(g) + O(g)
The following mechanism has been proposed for the gas-phase reaction of H2 with ICl:H2(g) + ICl(g) → HI(g) + HCl(g)HI(g) + ICl(g) → I2(g) + HCl(g)Write rate laws for each elementary reaction in the mechanism.
The following mechanism has been proposed for the gas-phase reaction of H2 with ICl:H2(g) + ICl(g) → HI(g) + HCl(g)HI(g) + ICl(g) → I2(g) + HCl(g)If the first step is slow and the second one is fast, what rate law do you expect to be observed for the overall reaction?
Consider the hypothetical reaction 2 A + B → 2 C + D. The following two-step mechanism is proposed for the reaction:Step 1: A + B → C + XStep 2: A + X → C + DX is an unstable intermediate.What is the predicted rate law expression if Step 1 is rate determining?
You have studied the gas-phase oxidation of HBr by O2:4HBr(g) + O2 (g) → 2H2O(g) + 2Br2 (g)You find the reaction to be first order with respect to HBr and first order with respect to O2. You propose the following mechanism:HBr(g) + O2 (g) → HOOBr(g)HOOBr(g) + HBr(g) → 2HOBr(g) HOBr(g) + HBr(g) → H2O(g) + Br2 (g)Based on the rate law, which step is rate determining?
Consider the hypothetical reaction 2 A + B → 2 C + D. The following two-step mechanism is proposed for the reaction:Step 1: A + B → C + XStep 2: A + X → C + DX is an unstable intermediate.What is the predicted rate law expression if Step 2 is rate determining?
Consider the hypothetical reaction 2 A + B → 2 C + D. The following two-step mechanism is proposed for the reaction:Step 1: A + B → C + XStep 2: A + X → C + DX is an unstable intermediate.What is the predicted rate law expression if Step 2 is rate determining? Your result for might be considered surprising for which of the following reasons?(i) The concentration of a product is in the rate law.(ii) There is a negative reaction order in the rate law.(iii) Both reasons (i) and (ii).(iv) Neither reasons (i) nor (ii).
Sulfonation of benzene has the following mechanism:(1) 2H2SO4 ⟶ H3O+ + HSO4- + SO3                                      [fast](2) SO3 + C6H6 ⟶ H(C6H5+)SO3-                                                        [slow](3) H(C6H5+)SO3- + HSO4- ⟶ C6H5SO3- + H2SO4                [fast](4) C6H5SO3- + H3O+ ⟶  C6H5SO3H + H2O                         [fast](b) Write the overall rate law in terms of the initial rate of the reaction.
A proposed mechanism for a reaction isWrite the rate law expected for this mechanism. What is the overall balanced equation for the reaction? What are the intermediates in the proposed mechanism?
The mechanism for the gas-phase reaction of nitrogen dioxide with carbon monoxide to form nitric oxide and carbon dioxide is thought to be Write the rate law expected for this mechanism. What is the overall balanced equation for the reaction?
The proposed mechanism for the formation of hydrogen bromide can be written in a simplified form as:Br2(g)  ⇌ 2 Br(g)          Fast, k1 (forward), k–1 (reverse)Br(g) + H2(g) → HBr(g) + H(g)          Slow, k2H(g) + Br2(g) → HBr(g) +  Br(g)          Slow, k3What rate law corresponds to this mechanism?
A proposed mechanism for the formation of hydrogen iodide can be written in simplified form asI2 → 2I          Fast, k1 (forward), k–1 (reverse)I + H2 ⇌ H2I          Fast, k2 (forward), k–2 (reverse)H2I + I →{uildrelover longrightarrow }atop {uildrel { k_5} over ;}  2 HI          Slow, k3What rate law corresponds to this mechanism?
The following mechanism has been proposed for the reaction of NO with H2 to form N2O and H2O:NO(g) + NO(g)2 → N2O2 (g)N2 O2 (g) + H2 (g) → N2O(g) + H2O(g)Write a rate law for first elementary reaction in the mechanism.
Phosgene (Cl2CO), a poison gas used in World War I, is formed by the reaction of Cl2 and CO. The proposed mechanism for the reaction is Cl2 ⇌ 2 Cl     (fast, equilibrium) Cl + CO ⇌ ClCO     (fast, equilibrium)ClCO + Cl2 → Cl2CO + Cl     (fast)What rate law is consistent with this mechanism?
The following mechanism has been proposed for the reaction of NO with H2 to form N2O and H2O:NO(g) + NO(g)2 → N2O2 (g)N2 O2 (g) + H2 (g) → N2O(g) + H2O(g)The observed rate law is rate = k[NO]2 [H2 ]. If the proposed mechanism is correct, what can we conclude about the relative speeds of the first and second reactions?
The following mechanism has been proposed for the reaction of NO with H2 to form N2O and H2O:NO(g) + NO(g)2 → N2O2 (g)N2 O2 (g) + H2 (g) → N2O(g) + H2O(g)Write a rate law for second elementary reaction in the mechanism.
In a hydrocarbon solution, the gold compound (CH3)3AuPH3 decomposes into ethane (C2H6) and a different gold compound, (CH3)AuPH3. The following mechanism has been proposed for the decomposition of (CH3)3AuPH3:Step 1: (CH3)3AuPH3 ⇌ (CH3)3Au + PH3 (fast, k1: forward; k–1: reverse)Step 2: (CH3)3Au → C2H6 + (CH3)Au (slow, k2)Step 3: (CH3)Au + PH3 → (CH3)AuPH3 (fast, k3)What is the rate law predicted by this mechanism?
In a hydrocarbon solution, the gold compound (CH3)3AuPH3 decomposes into ethane (C2H6) and a different gold compound, (CH3)AuPH3. The following mechanism has been proposed for the decomposition of (CH3)3AuPH3:Step 1: (CH3)3AuPH3 ⇌ (CH3)3Au + PH3 (fast, k1: forward; k–1: reverse)Step 2: (CH3)3Au → C2H6 + (CH3)Au (slow, k2)Step 3: (CH3)Au + PH3 → (CH3)AuPH3 (fast, k3)What would be the effect on the reaction rate of adding PH3 to the solution of (CH3)3AuPH3?
Consider this three-step mechanism for a reaction:What is the predicted rate law?
The oxidation of SO2 to SO3 is accelerated by NO2. The reaction proceeds according to:NO2(g) + SO2(g) → NO(g) + SO3(g)2 NO(g) + O2(g) → 2 NO2(g)Show that, with appropriate coefficients, the two reactions can be summed to give the overall oxidation of SO2 by O2 to give SO3. Give the equation for the final overall oxidation of SO2 by O2 to give SO3 as your answer.
The mechanism shown here is proposed for the gas phase reaction, 2 N2O5 → 4 NO2 + O2. What rate law does the mechanism predict?N2 O5 ⇌ NO2 + NO3          Fast, k1 (forward), k-1 (reverse),NO2 + NO3 → NO2 + O2 + NO          SlowNO + N2O5 → 3 NO2          Fasta) Rate = k[N2O5]b) Rate = k[N2O5]2c) Rate = k[N2O5]0d) Rate = k[NO2][NO3]
The gas-phase decomposition of ozone is thought to occur by the following two-step mechanism.Step 1: O3(g) ⇌ O2(g) + O(g) (fast)Step 2: O(g) + O3(g) → 2 O2(g) (slow)Derive the rate law that is consistent with this mechanism. (Hint: The product appears in the rate law.)
The gas-phase decomposition of ozone is thought to occur by the following two-step mechanism.Step 1: O3(g) ⇌ O2(g) + O(g) (fast)Step 2: O(g) + O3(g) → 2 O2(g) (slow)If instead the reaction occurred in a single step, would the rate law change? If so, what would it be?
The proposed mechanism for a reaction is(1) A(g) + B(g) ⇌ X(g)       [fast](2) X(g) + C(g) ⟶Y(g)      [slow](3) Y(g) ⟶ D(g)                [fast](d) Is the mechanism consistent with the actual rate law: Rate = k[A][B][C]?
Consider the following two-step mechanism for a reaction:NO2 (g) + Cl2(g) → ClNO2(g) + Cl(g)          k1, slowNO2 (g) + Cl(g) → ClNO2(g)          k2, fastWhat is the predicted rate law?
Consider the following mechanism:(1) ClO-(aq) + H2O(l) ⇌ HClO(aq) + OH-(aq)         [fast](2) I-(aq) + HClO(aq) ⟶ HIO(aq) + Cl-(aq)           [slow](3) OH-(aq) + HIO(aq) ⟶ H2O(l) + IO-(aq)           [fast](d) Is the mechanism consistent with the actual rate law: Rate =k[ClO-][I-]?
In the lower atmosphere, one of the mechanisms proposed for the decomposition of ozone to produce oxygen, 2 O3 ⟶ 3 O 2, is(1) O3 ⇌ O 2 + O(2) O + O 3 ⟶ 2 O 2 Use the steady-state approximation to write the rate law, assuming that step 2 is the rate-determining step.
In the lower atmosphere, one of the mechanisms proposed for the decomposition of ozone to produce oxygen, 2 O3 ⟶ 3 O 2, is(1) O3 ⇌ O 2 + O(2) O + O 3 ⟶ 2 O 2 Use the steady-state approximation to write the rate law, assuming that step 2 is the rate-determining step.The experimentally determined rate law is rate = k[O 3]2/[O2]. How can the rate law derived in (a) be rewritten to explain the known rate law?
Consider the following mechanism for the decomposition of NO 2Cl to NO 2 and Cl 2:(1) NO2Cl ⇌ NO 2 + Cl(2) NO2Cl + Cl ⟶ NO 2 + Cl 2Use the steady-state approximation to express the rate of Cl 2 production.
Consider the following mechanism for the decomposition of NO 2Cl to NO 2 and Cl 2:(1) NO2Cl ⇌ NO 2 + Cl(2) NO2Cl + Cl ⟶ NO 2 + Cl 2How is the rate law simplified if step 1 is the rate-determining step?
Consider the following mechanism for the decomposition of NO 2Cl to NO 2 and Cl 2:(1) NO2Cl ⇌ NO 2 + Cl(2) NO2Cl + Cl ⟶ NO 2 + Cl 2How is the rate law simplified if step 2 is the rate-determining step?
The hydrolysis of the sugar sucrose to the sugars glucose and fructose, C12H22O11 + H2O ⟶ C6H12O6 + C6H12O6 follows a first-order rate equation for the disappearance of sucrose: Rate = k[C12H22O11] (The products of the reaction, glucose and fructose, have the same molecular formulas but differ in the arrangement of the atoms in their molecules.)(b) When a solution of sucrose with an initial concentration of 0.150 M reaches equilibrium, the concentration of sucrose is 1.65 × 10−7 M. How long will it take the solution to reach equilibrium at 27 °C in the absence of a catalyst? Because the concentration of sucrose at equilibrium is so low, assume that the reaction is irreversible.(c) Why does assuming that the reaction is irreversible simplify the calculation in part (b)?
In general, can we predict the effect of doubling the concentration of A on the rate of the overall reaction A + B ⟶ C ? Can we predict the effect if the reaction is known to be an elementary reaction?
Given the following reactions and the corresponding rate laws, in which of the reactions might the elementary reaction and the overall reaction be the same?(a) Cl2 + CO ⟶ Cl2CO, rate = k[Cl2]3/2 [CO](b) PCl3 + Cl2 ⟶ PCl5, rate = k[PCl3][Cl2](c) 2 NO + H2 ⟶ N2 + H2O, rate = k[NO][H2](d) 2 NO + O2 ⟶ 2 NO2, rate = k[NO]2 [O2](e) NO + O3 ⟶ NO2 + O2, rate = k[NO][O3]
Reactions between certain haloalkanes (alkyl halides) and water produce alcohols. Consider the overall reaction for t-butyl bromide (2-bromo-2-methylpropane):(CH3)3CBr(aq) + H2O(l) ⟶ (CH3)3COH(aq) + H+(aq) + Br-(aq)The experimental rate law is rate = k[(CH3)3CBr]. The accepted mechanism for the reaction is(1) (CH3)3C—Br(aq) ⟶ (CH3)3C+(aq) + Br-(aq)                      [slow](2) (CH3)3C+(aq) + H2O(l) ⟶ (CH3)3C—OH2+(aq)                [fast](3) (CH3)3C—OH2+(aq) ⟶ H+(aq) + (CH3)3C—OH(aq)         [fast](b) Write rate laws for the elementary steps.
Write the rate equation for each of the following elementary reactions:(a) O3 O2 + O
Write the rate equation for each of the following elementary reactions:(b) O3 + Cl ⟶ O2 + ClO
Write the rate equation for each of the following elementary reactions:(c) ClO + O ⟶ Cl + O2
Write the rate equation for each of the following elementary reactions:(d) O3 + NO ⟶ NO2 + O2
Write the rate equation for each of the following elementary reactions:(e) NO2 + O ⟶ NO + O2
The reaction of CO with Cl2 gives phosgene (COCl2), a nerve gas that was used in World War I. Use the mechanism shown here to complete the following exercises:Cl2 (g) ⇌ 2 Cl (g) (fast, k1 represents the forward rate constant, k−1 the reverse rate constant)CO(g) + Cl(g) ⟶ COCl(g) (slow, k2 the rate constant)COCl(g) + Cl(g) ⟶ COCl2 (g) (fast, k3 the rate constant)(b) Identify all intermediates.
Ozone in the upper atmosphere can be destroyed by the following two-step mechanism:Cl(g) + O3(g) → ClO(g) + O2(g)ClO(g) + O(g) → Cl(g) + O2(g)What is the catalyst in the reaction?
Ozone in the upper atmosphere can be destroyed by the following two-step mechanism:Cl(g) + O3(g) → ClO(g) + O2(g)ClO(g) + O(g) → Cl(g) + O2(g)What is the intermediate in the reaction?
In 1995, Mario Molina, Paul Crutzen, and F. Sherwood Rowland shared the Nobel Prize in chemistry for their work on atmospheric chemistry. One reaction sequence they proposed for the role of chlorine in the decomposition of stratospheric ozone (we’ll see another sequence in Chapter 16) is(1) Cl(g) + O3(g) ⟶ ClO(g) + O2(g) (2) ClO(g) + ClO(g) ⟶ Cl2O2(g) (3) Cl2O2(g) light ⟶ 2 Cl(g) + O2(g) Over the tropics, O atoms are more common in the stratosphere:(4) ClO(g) + O(g) ⟶ Cl(g) + O2(g) Write an overall equation combining reactions 1–3.
One mechanism for the destruction of ozone in the upper atmosphere isb. Which species is an intermediate?
The Ostwald process for the commercial production of nitric acid from ammonia and oxygen involves the following steps:4NH3 (g) + 5O2 (g) → 4NO (g) + 6 H2O (g)2NO(g) + O2 (g) → 2NO2 (g)3NO2 (g) + H2O (l) → 2HNO3 (aq) + NO (g)a. Use the values of ΔH° f in Appendix 4 to calculate the value of ΔH° for each of the preceding reactionsb. Write the overall equation for the production of nitric acid by the Ostwald process by combining the preceding equations. (Water is also a product.) Is the overall reaction exothermic or endothermic?
The following mechanism has been proposed for the gas-phase reaction of H2 with ICl:H2(g) + ICl(g) → HI(g) + HCl(g)HI(g) + ICl(g) → I2(g) + HCl(g)Write the balanced equation for the overall reaction.
The following mechanism has been proposed for the gas-phase reaction of H2 with ICl:H2(g) + ICl(g) → HI(g) + HCl(g)HI(g) + ICl(g) → I2(g) + HCl(g)Identify any intermediates in the mechanism.
Isolation of Group 8B(10) elements, used as industrial catalysts, involves a series of steps. For nickel, the sulfide ore is roasted in air: Ni3S2(s) + O2(g) ⇌ NiO(s) + SO2(g). The metal oxide is reduced by the H2 in water gas (CO + H 2) to impure Ni: NiO(s) + H2(g) ⇌ Ni(s) + H2O(g). The CO in water gas then reacts with the metal in the Mond process to form gaseous nickel carbonyl, Ni(s) + CO(g) ⇌ Ni(CO)4(g), which is subsequently decomposed to the metal.(a) Balance each of the three steps, and obtain an overall balanced equation for the conversion of Ni3S2 to Ni(CO)4. 
You have studied the gas-phase oxidation of HBr by O2:4HBr(g) + O2 (g) → 2H2O(g) + 2Br2 (g)You find the reaction to be first order with respect to HBr and first order with respect to O2. You propose the following mechanism:HBr(g) + O2 (g) → HOOBr(g)HOOBr(g) + HBr(g) → 2HOBr(g) HOBr(g) + HBr(g) → H2O(g) + Br2 (g)What are the intermediates in this mechanism?
The interhalogen ClF3 is prepared via a two-step fluorination of chlorine gas:Cl2(g) + F2(g) ⥫⥬ ClF(g)ClF(g) + F2(g) ⥫⥬ ClF3(g)(a) Balance each step and write the overall equation.
The following mechanism has been proposed for the reaction of NO with H2 to form N2O and H2O:NO(g) + NO(g)2 → N2O2 (g)N2 O2 (g) + H2 (g) → N2O(g) + H2O(g)Identify any intermediates in the mechanism.
In a hydrocarbon solution, the gold compound (CH3)3AuPH3 decomposes into ethane (C2H6) and a different gold compound, (CH3)AuPH3. The following mechanism has been proposed for the decomposition of (CH3)3AuPH3:Step 1: (CH3)3AuPH3 ⇌ (CH3)3Au + PH3 (fast, k1: forward; k–1: reverse)Step 2: (CH3)3Au → C2H6 + (CH3)Au (slow, k2)Step 3: (CH3)Au + PH3 → (CH3)AuPH3 (fast, k3)What are the intermediates in the mechanism?
Consider this three-step mechanism for a reaction:Identify the intermediates in the mechanism.
For the reaction ABC + D ⇌ AB + CD, ΔH°rxn = −55 kJ/mol and Ea(fwd) = 215 kJ/mol. Assuming a one-step reaction,and (c) sketch a possible transition state if ABC is V shaped.
The oxidation of SO2 to SO3 is accelerated by NO2. The reaction proceeds according to:NO2(g) + SO2(g) → NO(g) + SO3(g)2 NO(g) + O2(g) → 2 NO2(g)Do we consider NO2 a catalyst or an intermediate in this reaction?
The oxidation of SO2 to SO3 is accelerated by NO2. The reaction proceeds according to:NO2(g) + SO2(g) → NO(g) + SO3(g)2 NO(g) + O2(g) → 2 NO2(g)Would you classify NO as a catalyst or as an intermediate?
For the reaction A2 + B2 ⟶2AB, Ea(fwd) = 125 kJ/mol and Ea(rev) = 85 kJ/mol. Assuming the reaction occurs in one step(c) sketch a possible transition state.
The gas-phase decomposition of ozone is thought to occur by the following two-step mechanism.Step 1: O3(g) ⇌ O2(g) + O(g) (fast)Step 2: O(g) + O3(g) → 2 O2(g) (slow)Write the balanced equation for the overall reaction.
The gas-phase decomposition of ozone is thought to occur by the following two-step mechanism.Step 1: O3(g) ⇌ O2(g) + O(g) (fast)Step 2: O(g) + O3(g) → 2 O2(g) (slow)Is O a catalyst or an intermediate?
Aqua regia, a mixture of HCl and HNO3, has been used since alchemical times to dissolve many metals, including gold.Its orange color is due to the presence of nitrosyl chloride. Consider this one-step reaction for the formation of this compound:NO(g) + Cl2(g) ⟶NOCl(g) + Cl(g)                    ΔH° = 83 kJ(c) Sketch a possible transition state for the reaction. (Note: The atom sequence of nitrosyl chloride is Cl—N—O.)
The proposed mechanism for a reaction is(1) A(g) + B(g) ⇌ X(g)       [fast](2) X(g) + C(g) ⟶Y(g)      [slow](3) Y(g) ⟶ D(g)                [fast](b) Identify the intermediate(s), if any.
Consider the following two-step mechanism for a reaction:NO2 (g) + Cl2 (g) → ClNO2 (g) + Cl(g)NO2 (g) + Cl(g) → ClNO2 (g)Identify the intermediates in the mechanism.
Consider the following mechanism:(1) ClO-(aq) + H2O(l) ⇌ HClO(aq) + OH-(aq)         [fast](2) I-(aq) + HClO(aq) ⟶ HIO(aq) + Cl-(aq)           [slow](3) OH-(aq) + HIO(aq) ⟶ H2O(l) + IO-(aq)           [fast](b) Identify the intermediate(s), if any.
One mechanism for the destruction of ozone in the upper atmosphere isa. Which species is a catalyst?
A (green), B (blue), and C (red) are structural isomers. The molecular filmstrip depicts them undergoing a chemical change as time proceeds.What role does C play?
Suppose we have two reactions, A → B and B → C. You can isolate B, and it is stable. Is B the transition state for the reaction A → C?
Reactions between certain haloalkanes (alkyl halides) and water produce alcohols. Consider the overall reaction for t-butyl bromide (2-bromo-2-methylpropane):(CH3)3CBr(aq) + H2O(l) ⟶ (CH3)3COH(aq) + H+(aq) + Br-(aq)The experimental rate law is rate = k[(CH3)3CBr]. The accepted mechanism for the reaction is(1) (CH3)3C—Br(aq) ⟶ (CH3)3C+(aq) + Br-(aq)                      [slow](2) (CH3)3C+(aq) + H2O(l) ⟶ (CH3)3C—OH2+(aq)                [fast](3) (CH3)3C—OH2+(aq) ⟶ H+(aq) + (CH3)3C—OH(aq)         [fast](c) What reaction intermediates appear in the mechanism?
The rate law for the reactionNO2(g) + CO(g) ⟶NO(g) + CO2(g)is rate = k[NO2]2; one possible mechanism is shown in Section 16.6.(b) Consider the following alternative mechanism:(1) 2NO2(g) ⟶ N2(g) + 2O2(g)         [slow](2) 2CO(g) + O2(g) ⟶2CO2(g)        [fast](3) N2(g) + O2(g) ⟶2NO(g)            [fast]Is the alternative mechanism consistent with the rate law? Is one mechanism more reasonable physically? Explain.
Experiments were conducted to study the rate of the reaction represented by this equation.[2] 2 NO(g) + 2 H2(g) ⟶ N2(g) + 2 H2O(g) Initial concentrations and rates of reaction are given here.Consider the following questions:(e) The following sequence of elementary steps is a proposed mechanism for the reaction.Step 1: NO + NO ⇌ N2O2 Step 2: N2O2 + H2 ⇌ H2O + N2OStep 3: N2O + H2 ⇌ N2 + H2OBased on the data presented, which of these is the rate determining step? Show that the mechanism is consistent with the observed rate law for the reaction and the overall stoichiometry of the reaction.
The reaction of CO with Cl2 gives phosgene (COCl2), a nerve gas that was used in World War I. Use the mechanism shown here to complete the following exercises: Cl2 (g) ⇌ 2 Cl (g) (fast, k1 represents the forward rate constant, k−1 the reverse rate constant) CO(g) + Cl(g) ⟶ COCl(g) (slow, k2 the rate constant) COCl(g) + Cl(g) ⟶ COCl2 (g) (fast, k3 the rate constant) (a) Write the overall reaction.
Ozone in the upper atmosphere can be destroyed by the following two-step mechanism:Cl(g) + O3(g) → ClO(g) + O2(g)ClO(g) + O(g) → Cl(g) + O2(g)What is the overall equation for this process?
Experiment shows that the rate of formation of carbon tetrachloride from chloroform,CHCl3(g) + Cl2(g) ⟶CCl4(g) + HCl(g)is first order in CHCl3, 1/2 order in Cl2, and 3/2 order overall. Show that the following mechanism is consistent with the rate law:(1) Cl2(g) ⇌ 2Cl(g)                                                 [fast](2) Cl(g) + CHCl3(g) ⟶HCl(g) + CCl3(g)               [slow](3) CCl3(g) + Cl(g) ⟶CCl4(g)                                 [fast]
The overall equation and rate law for the gas-phase decomposition of dinitrogen pentoxide are2 N2O5(g) ⟶ 4 NO2(g) + O 2(g)               rate = k[N  2O5]Which of the following can be considered valid mechanisms for the reaction?I – One-step collisionII – 2 N 2O5(g) ⟶ 2 NO 3(g) + 2 NO 2(g)     [slow]      2 NO 3(g) ⟶ 2 NO 2(g) + 2 O (g)     [fast]               2 O  (g) ⟶ O 2(g)      [fast]III – N 2O5(g) ⇌ NO 3(g) + NO 2(g)     [fast]       NO 2(g) + N 2O5(g) ⟶ 3 NO 2(g) + O(g)     [slow]                 NO 3(g) + O(g) ⟶ NO2(g) + O2(g)     [fast]IV – 2 N 2O5(g) ⇌ 2 NO 2(g) + N2O3(g) + 3 O (g)     [fast]        N 2O3(g) + O(g) ⟶ 2 NO 2(g)     [slow]        2 O (g) ⟶ O 2(g)     [fast]V – 2 N2O5(g) ⟶ N4O10(g)               [slow]       N 4O10(g) ⟶ 4 NO2(g) + O 2(g)     [fast]
You may want to reference (Pages 593 - 600)Section 14.6 while completing this problem.Consider the following reaction: 2 A + B → X + 2 Y. You are told that the first step in the mechanism of this reaction has the following rate law: Rate = k[A][B]. Which of the following could be the first step in the reaction mechanism (note that substance Z is an intermediate)?(a) A + A → Y + Z(b) A → X + Z(c) A + A + B → X + Y + Y(d) B → X + Y(e) A + B → X + Z
Even when a mechanism is consistent with the rate law, later work may show it to be incorrect. For example, the reaction between hydrogen and iodine has this rate law: rate = k[H2][I2]. The long-accepted mechanism had a single bimolecular step; that is, the overall reaction was thought to be elementary:H2(g) + I2(g) ⟶ 2HI(g)In the 1960s, however, spectroscopic evidence showed the presence of free I atoms during the reaction. Kineticists have since proposed a three-step mechanism:(1) I2(g) ⇌ 2I(g)                            [fast](2) H2(g) + I(g) ⇌ H2I(g)              [fast](3) H2I(g) + I(g) ⟶2HI(g)            [slow]Show that this mechanism is consistent with the rate law.
At a certain time in a reaction, substance A is disappearing at a rate of 4.010-2 M/s, substance B is appearing at a rate of 2.010-2 M/s, and substance C is appearing at a rate of 6.010-2 M/s. Which of the following could be the stoichiometry for the reaction being studied?
You have studied the gas-phase oxidation of HBr by O2:4HBr(g) + O2 (g) → 2H2O(g) + 2Br2 (g)You find the reaction to be first order with respect to HBr and first order with respect to O2. You propose the following mechanism:HBr(g) + O2 (g) → HOOBr(g)HOOBr(g) + HBr(g) → 2HOBr(g) HOBr(g) + HBr(g) → H2O(g) + Br2 (g)If you are unable to detect HOBr or HOOBr among the products, does this disprove your mechanism?
Sulfonation of benzene has the following mechanism:(1) 2H2SO4 ⟶ H3O+ + HSO4- + SO3                                      [fast](2) SO3 + C6H6 ⟶ H(C6H5+)SO3-                                                        [slow](3) H(C6H5+)SO3- + HSO4- ⟶ C6H5SO3- + H2SO4                [fast](4) C6H5SO3- + H3O+ ⟶  C6H5SO3H + H2O                         [fast](a) Write an overall equation for the reaction. 
A possible mechanism for the decomposition of hydrogen peroxide isH2O2 → 2OHH2O2 + OH → H2O + HO2HO2 + OH → H2O + O2Using your results from Exercise 37, specify which step is the rate-determining step. What is the overall balanced equation for the reaction?---------------------Exercise 37. The decomposition of hydrogen peroxide was studied, and the following data were obtained at a particular temperature:Assuming thatdetermine the rate law, the integrated rate law, and the value of the rate constant. Calculate [H2O2] at 4000. s after the start of the reaction.
Consider the gas-phase reaction: H2(g) + I2(g) → 2 HI(g)The reaction was experimentally determined to be first order in H2 and first order in I2. Consider the proposed mechanisms.Proposed mechanism I: H2(g) + I2(g) → 2 HI(g) Single stepProposed mechanism II:I2(g) → 2 I(g)          FastH2(g) + 2 I(g) → {uildreloverlongrightarrow} atop {uildrel { k_3} over ;} 2 HI(g)          SlowShow that the first of the proposed mechanisms is valid.
Consider the gas-phase reaction: H2(g) + I2(g) → 2 HI(g)The reaction was experimentally determined to be first order in H2 and first order in I2. Consider the proposed mechanisms.Proposed mechanism I: H2(g) + I2(g) → 2 HI(g) Single stepProposed mechanism II:I2(g) → 2 I(g)          FastH2(g) + 2 I(g) → 2 HI(g)          SlowWhat kind of experimental evidence might lead you to favor mechanism II over mechanism I?
Consider the gas-phase reaction: H2(g) + I2(g) → 2 HI(g)The reaction was experimentally determined to be first order in H2 and first order in I2. Consider the proposed mechanisms.Proposed mechanism I: H2(g) + I2(g) → 2 HI(g) Single stepProposed mechanism II:I2(g) → 2 I(g)          FastH2(g) + 2 I(g) → 2 HI(g)          SlowIs the second of the proposed mechanisms valid?
In a hydrocarbon solution, the gold compound (CH3)3AuPH3 decomposes into ethane (C2H6) and a different gold compound, (CH3)AuPH3. The following mechanism has been proposed for the decomposition of (CH3)3AuPH3:Step 1: (CH3)3AuPH3 ⇌ (CH3)3Au + PH3 (fast, k1: forward; k–1: reverse)Step 2: (CH3)3Au → C2H6 + (CH3)Au (slow, k2)Step 3: (CH3)Au + PH3 → (CH3)AuPH3 (fast, k3)What is the overall reaction?
In a hydrocarbon solution, the gold compound (CH3)3AuPH3 decomposes into ethane (C2H6) and a different gold compound, (CH3)AuPH3. The following mechanism has been proposed for the decomposition of (CH3)3AuPH3:Step 1: (CH3)3AuPH3 ⇌ (CH3)3Au + PH3 (fast, k1: forward; k–1: reverse)Step 2: (CH3)3Au → C2H6 + (CH3)Au (slow, k2)Step 3: (CH3)Au + PH3 → (CH3)AuPH3 (fast, k3)What is the rate-determining step?
Consider the following reaction to produce methyl acetate:When this reaction is carried out with CH 3OH containing oxygen-18, the water produced does not contain oxygen-18. Explain.
A chemist studied the reaction mechanism for the reaction:2NO(g) + O2(g) → 2NO2(g)by reacting N16O with 18O2. If the reaction mechanism isNO + O2 ⇌ NO3 (fast equilibrium)NO3 + NO → 2NO 2 (slow)what distribution of 18O would you expect in the NO 2? Assume that N is the central atom in NO 3, assume only N16O18O2 forms, and assume stoichiometric amounts of reactants are combined.
Consider this overall reaction, which is experimentally observed to be second order in AB and zero order in C: AB + C → A + BCIs the following mechanism valid for this reaction?
Consider this overall reaction, which is experimentally observed to be second order in X and first order in Y: X + Y → XYIs this two-step mechanism valid?
Consider this three-step mechanism for a reaction:What is the overall reaction?
We have seen a number of reactions in which a single reactant forms products. For example, consider the following first-order reaction: CH3NC(g) → CH3CN(g). However, we also learned that gas-phase reactions occur through collisions.Another possibility is that the reaction occurs through more than one step. For example, a possible mechanism involves one step in which the two CH3NC molecules collide, resulting in the "activation" of one of them. In a second step, the activated molecule goes on to form the product. Determine which step must be rate determining in order for the kinetics of the reaction to be first order.
The proposed mechanism for a reaction is(1) A(g) + B(g) ⇌ X(g)       [fast](2) X(g) + C(g) ⟶Y(g)      [slow](3) Y(g) ⟶ D(g)                [fast](a) What is the overall equation?
The proposed mechanism for a reaction is(1) A(g) + B(g) ⇌ X(g)       [fast](2) X(g) + C(g) ⟶Y(g)      [slow](3) Y(g) ⟶ D(g)                [fast](e) Is the following one-step mechanism equally valid? A(g) + B(g) + C(g) ⟶ D(g)?
Consider the following two-step mechanism for a reaction:NO2 (g) + Cl2 (g) → ClNO2 (g) + Cl(g)NO2 (g) + Cl(g) → ClNO2 (g)What is the overall reaction?
Consider the following mechanism:(1) ClO-(aq) + H2O(l) ⇌ HClO(aq) + OH-(aq)         [fast](2) I-(aq) + HClO(aq) ⟶ HIO(aq) + Cl-(aq)           [slow](3) OH-(aq) + HIO(aq) ⟶ H2O(l) + IO-(aq)           [fast](a) What is the overall equation?
In a study of nitrosyl halides, a chemist proposes the following mechanism for the synthesis of nitrosyl bromide:NO(g) + Br2(g) ⇌ NOBr2(g)               [fast]NOBr2(g) + NO(g) ⟶ 2NOBr(g)        [slow]If the rate law is rate = k[NO]2[Br2], is the proposed mechanism valid? If so, show that it satisfies the three criteria for validity.
Figure 16.25 shows key steps in the metal-catalyzed (M) hydrogenation of ethene:C2H4(g) + H2(g) ⟶ C2H6(g)Use the following symbols to write a mechanism that gives the overall equation:H2(ads) – adsorbed hydrogen moleculesM–H – hydrogen atoms bonded to metal atomsC2H4(ads) – adsorbed ethene moleculesC2H5(ads) – adsorbed ethyl radicals
The rate law for 2NO(g) + O2(g) ⟶ 2NO2(g) is rate = k[NO]2[O2]. In addition to the mechanism in the text (Section 16.6), the following ones have been proposed:I        2NO(g) + O2(g) ⟶2NO2(g)II       2NO(g) ⇌ N2O2(g)                          [fast]         N2O2(g) + O2(g) ⟶2NO2(g)           [slow]III      2NO(g) ⇌ N2(g) + O2(g)                  [fast]         N2(g) + 2O2(g) ⟶ 2NO2(g)            [slow](a) Which of these mechanisms is consistent with the rate law?
The rate law for 2NO(g) + O2(g) ⟶ 2NO2(g) is rate = k[NO]2[O2]. In addition to the mechanism in the text (Section 16.6), the following ones have been proposed:I        2NO(g) + O2(g) ⟶2NO2(g)II       2NO(g) ⇌ N2O2(g)                          [fast]         N2O2(g) + O2(g) ⟶2NO2(g)           [slow]III      2NO(g) ⇌ N2(g) + O2(g)                  [fast]         N2(g) + 2O2(g) ⟶ 2NO2(g)            [slow](b) Which of these mechanisms is most reasonable? Why?
A (green), B (blue), and C (red) are structural isomers. The molecular filmstrip depicts them undergoing a chemical change as time proceeds.Write a mechanism for the reaction.
Assuming that the mechanism for the hydrogenation of C 2H4 given below is correct, would you predict that the product of the reaction of C2H4 with D2 would be CH2D—CH2D or CHD2—CH3? How could the reaction of C2H4 with D2 be used to confirm the mechanism for the hydrogenation of C2H4 given below?Heterogeneous catalysis of the hydrogenation of ethylene. (a) The reactants above the metal surface. (b) Hydrogen is adsorbed onto the metal surface, forming metal–hydrogen bonds and breaking the H—H bonds. The π bond in ethylene is broken and metal–hydrogen bonds are formed during adsorption. (c) The adsorbed molecules and atoms migrate toward each other on the metal surface, forming new C—H bonds. (d) The C atoms in ethane (C2H6) have completely saturated bonding capacities and so cannot bind strongly to the metal surfaces. The C2H6 molecule thus escapes.
The following diagrams represent mixtures of NO(g) and O2(g). These two substances react as follows:2 NO ( g ) + O2 ( g ) → 2 NO2 ( g )It has been determined experimentally that the rate is second order in NO and first order in O2.Based on this fact, which of the following mixtures will have the fastest initial rate?
Iodomethane (CH3I) is a commonly used reagent in organic chemistry. When used properly, this reagent allows chemists to introduce methyl groups in many different useful applications. The chemical does pose a risk as a carcinogen, possibly owing to iodomethane’s ability to react with portions of the DNA strand (if they were to come in contact). Consider the following hypothetical initial rates data:Which of the following could be a possible mechanism to explain the initial rate data?
Define these terms:(c) elementary reaction
Define these terms:(d) overall reaction
Reactions between certain haloalkanes (alkyl halides) and water produce alcohols. Consider the overall reaction for t-butyl bromide (2-bromo-2-methylpropane):(CH3)3CBr(aq) + H2O(l) ⟶ (CH3)3COH(aq) + H+(aq) + Br-(aq)The experimental rate law is rate = k[(CH3)3CBr]. The accepted mechanism for the reaction is(1) (CH3)3C—Br(aq) ⟶ (CH3)3C+(aq) + Br-(aq)                      [slow](2) (CH3)3C+(aq) + H2O(l) ⟶ (CH3)3C—OH2+(aq)                [fast](3) (CH3)3C—OH2+(aq) ⟶ H+(aq) + (CH3)3C—OH(aq)         [fast](a) Why doesn’t H2O appear in the rate law?
Reactions between certain haloalkanes (alkyl halides) and water produce alcohols. Consider the overall reaction for t-butyl bromide (2-bromo-2-methylpropane):(CH3)3CBr(aq) + H2O(l) ⟶ (CH3)3COH(aq) + H+(aq) + Br-(aq)The experimental rate law is rate = k[(CH3)3CBr]. The accepted mechanism for the reaction is(1) (CH3)3C—Br(aq) ⟶ (CH3)3C+(aq) + Br-(aq)                      [slow](2) (CH3)3C+(aq) + H2O(l) ⟶ (CH3)3C—OH2+(aq)                [fast](3) (CH3)3C—OH2+(aq) ⟶ H+(aq) + (CH3)3C—OH(aq)         [fast](d) Show that the mechanism is consistent with the experimental rate law.
Consider the following mechanismStep 1: A → B+C     EquilibriumStep 2: C+D → E    Slow______________________________Overall: A + D → B + EWhat is the rate law for the overall reaction?
Consider the following mechanism.step 1:      A + B ⇌ C equilibriumstep 2:      C + A → D slow——————————————overall:      2A + B → DDetermine the rate law for the overall reaction (where the overall rate constant is represented as k).
Consider the following elementary reaction equation.NO3(g) + CO(g) → NO2(g) + CO2(g)a. What is the order with respect of NO3?b. What is the overall order of the reaction?c. Classify the reaction as unimolecular, bimolecular, or termolecular.