Kinetics          Quiz #5                        Mechanisms               Answers

 

1.  Consider the following reaction mechanism

Step 1: M + X   → MX

                        Step 2: MX + A   → D  + X 

The chemical species MX is a(n)

 

            A.        Catalyst

            B.         Inhibitor

            C.        Final Product

            D.        Reaction Intermediate

 

2.  Consider the following reaction mechanism

                        Step 1: NO2 + NO2   → NO + NO3

                        Step 2: NO3 + CO   → NO2 + CO2

The overall reaction is

   

            A.        2NO2   → NO3 + NO

            B.        NO2 + CO   → NO + CO2

            C.        NO3 + CO   → NO2 + CO2

            D.        NO2 + NO3 + CO   → NO3 + NO2 + NO + CO2

 

3. Consider the following reaction mechanism

                        Step 1: V3+    + Cu2+   → V4+      + Cu+             (slow)

                        Step 2: Cu+ + Fe3+    → Cu2+ + Fe2+     (fast)

The reaction intermediate is

 

A.        Cu+

B.         Cu2+

C.        V3+

D.        Fe3+

 

4. Consider the following reaction Mechanism

                        Step 1: H2O2 + I -    →   H2O + IO-

                        Step 2: H2O2 + IO -    →   H2O + O2 + I -                    

The reaction intermediate is

 

            A.        I -

            B.        IO -

            C.        H2O

            D.        H2O2

 

 

5.  Consider the following potential energy diagram

 

 

 

 

 

 

 

 

 

 


  

The above potential energy diagram represents an

 

            A.        Exothermic reaction involving one step

            B.        Exothermic reaction involving two steps

            C.        Endothermic reaction involving one step

            D.        Endothermic reaction involving two steps

 

6.  Consider the following reaction mechanism

                        Step 1: NO2(g)  + NO2(g)     →  NO(g)    +  NO3(g)    (slow)

                        Step 2: NO3(g)  + CO(g)      →  CO2(g)   + NO2(g)      (fast)

Which one of the following changes would result in the greatest increase in reaction rate

 

            A.        Increase [CO]

            B.         Decrease [NO]

            C.        Increase [NO2]

            D.        Increase [NO3]

 

7. An uncatalyzed reaction was found to produce 40 kJ of energy in 10 mins. When catalyzed, the same reaction produced 40 kJ of energy in 2 mins. Which one of the following potential energy diagrams is consistent with the above data?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


8. Consider the following reaction mechanism

                       

Step 1: ICl + H2    →    HI  + HCl (slow)

                        Step 2: ICl + HI    →    HCl  + I2   (fast)

 

The Species HCl is a

           

A.        Product

            B.         Catalyst

            C.        Reactant

            D.        Reaction Intermediate

 

9.  Consider the following reaction mechanism

                        Step 1: Cl(g)   + O3(g)       →  ClO(g)  + O2(g)

                        Step 2:  O(g)  + ClO(g)    →  Cl(g)     + O2(g)

The Reaction intermediate is

 

            A.        Cl

            B.         O2

            C.        O3

            D.        ClO

 

10. In a reaction mechanism, the rate determining step is the 

 

            A.        Fastest and has the lowest reaction rate.

            B.         Fastest and has the highest activation energy

            C.        Slowest and has the lowest activation energy

            D.        Slowest and has the highest activation energy

 

 

 

 

 

 

 

 

 

 

 

 

 


11. Select the true statement concerning the above potential energy diagram.

 

            A.        The catalyzed reaction has a larger ∆H

            B.         The uncatalyzed reaction has a larger ∆H

            C.        The catalyzed reaction has a greater rate of reaction

            D.        The uncatalyzed reaction has a greater rate of reaction

 

 

12. Which point on the diagram above represents the potential energy of the activated complex formed in the uncatalyzed reaction?

 

           

 

 

 

 

 

 

 

 

 

 

 

 

 


A.        I

            B.         II

            C.        III

            D.        IV

 

13.  Consider the following reaction

                        Step 1: NO(g)  +  O3(g)  ------ >  NO2(g)  + O2(g)

                                Step 2: O(g)  + NO2(g)  ------ > NO(g)  + O2(g)

            The catalyst is

  

            A.        O2

            B.         O3

            C.        NO

            D.        NO2

 

14. Consider the following reaction mechanism

                        Step 1: N2O(g)  ------ > N2(g)  +  O(g)

                        Step 2: N2O(g)  +  O(g)  ------ >  N2(g) +  O2(g)

            The reactant in the overall reaction is

 

            A.        O

            B.         O2

            C.        N2

            D.        N2O

 

15. Consider the following reaction

                        O3(g)  + NO(g)  ----- > NO2(g)  +  O2(g)

                        NO2(g)  + O(g)  ------ > NO(g)  +  O2(g)

The product in the overall reaction is

 

            A.        O2

            B.         O3

            C.        NO

            D.        NO2

 

 

Use the following reaction mechanism to answer questions 16 and 17.

Step 1:             2PO       →      P2O2                                                    (fast)

Step 2:             P2O2    +          H2        →        P2O      +     H2O          (slow)

Step 3:             P2O      +          H2        →        P2         +     H2O          (fast)

 

16.       Increasing the concentration of which of the following substances would cause the greatest increase in the reaction rate?

            A.        H2

            B.         PO

            C.        P2O

            D.        H2O

 

17.       Which of the following are products in the overall reaction?

            I           P2

            II          P2O2

            III        PO2

            IV        H2O

            A.        I and II only

            B.        I and IV only

            C.        II and III only

            D.        III and IV only

 

18.       The Intermediates are:

            A.        NO                  H2

            B.         H2O                 P2

            C.        P2O2                PO

            D.        P2O2                P2O

 

19.       Which of the following could describe a catalyst?

            A.        A substance that increases the reaction time.

            B.         A substance that provides an alternate mechanism with higher activation energy.

            C.        A substance that is formed in one step and used up in a subsequent step in a reaction mechanism.

            D.        A substance that is used up in one step and reformed in a subsequent step in a reaction mechanism.

 

20.       Consider the following reaction: 2PO(g)   +   O2(g)     →     2PO2(g)

            Why would this reaction probably involve more than one step?

            A.        There is insufficient activation energy.

            B.         This reaction has high activation energy.

            C.        Reactions between gases are typically slow.

            D.        A successful collision between three molecules is unlikely.

 

 

 

 

21.       Consider the following reaction mechanism:

            Step 1              Cl3    →    Cl2       +      Cl

            Step 2              Cl3       +      Cl   →       2Cl2

            Which of the following could represent the activated complex for Step 2?

            A.        Cl

            B.         Cl2

            C.        Cl3

            D.        Cl4

 

22.       Consider the reaction:   2C4H10(g)   +   13O2(g)   →    8CO2(g)    +   10H2O(l)

            Which of the following explains, in terms of collision theory, why this reaction occurs in more than one step?

            A.        a low C4H12(g) pressure

            B.         low temperature of reactant mixture

            C.        low probability of a multi-particle collision

            D.        particles collide with insufficient kinetic energy

 

23.       Consider the following reaction mechanism and overall reaction:                        

            Step 1              ½ O2(g)   +  NO(g)         →    NO2(g)

                                                                      sunlight

            Step 2                          NO2(g)              →     NO(g)    +    O(g)

            Step 3              O2(g)   +  O(g)               →    O3(g)

           

            Overall                         3/2 O2 (g)              →    O3(g)

            What is the catalyst in this mechanism?

            A.        O

            B.        NO

            C.        NO2

            D.        sunlight

 

24.       What is an intermediate in this mechanism?

            A.        O

            B.         NO

            C.        O3

            D.        sunlight

 

25.       Consider the following reaction mechanism:

            Step 1                          NOI                 →        NO      +          I

            Step 2              NOI         +   I              →    NOI2

            Identify the reaction intermediate.

            A.        I

            B.         NOI2

            C.        NO

            D.        NOI

 

 

26.       Consider the following reaction mechanism:

            Step 1               2NO2  →        NO3     +          NO

            Step 2              NO3 +  CO      →        NO2   +   CO2

            Identify a product in the overall reaction.

            A.        CO

            B.        CO2

            C.        NO2

            D.        NO3

 

27.       Consider the following reaction mechanism:

            Step 1               2NO2  →        NO3     +          NO

            Step 2              NO3 +  CO      →        NO2   +   CO2

            Identify an intermediate.

            A.        CO

            B.         CO2

            C.        NO2

            D.        NO3