Name: XXXXXXXXXXDate: Chemistry 12 Module 1 Assignment 1. Note that there were four parts to the video (the iodine clock reaction, the effect of the nature of reactants on rate, the effect of a...

Name: XXXXXXXXXXDate:
Chemistry 12 Module 1 Assignment
1. Note that there were four parts to the video (the iodine clock reaction, the effect of the nature of reactants on rate, the effect of a catalyst on rate, and the effect of temperature on rate). For each part, record observations from the video that describe how these factors affect reaction rate. (2 marks)
IODINE CLOCK REACTION
2. For the iodine clock reaction, copy down the following chart and fill in the blanks.
    Trial
    [IO3-]
    Diluted [IO3-]
    Reaction time (s)
    Rate (M/s)
    1
    0.001M
     
    22
     
    2
    0.002M
     
    9
     
    3
    0.004M
     
    5
     
    4
    0.005M
     
    4
     
    5
    0.006M
     
    4
     
    6
    0.007M
     
    3.7
     
    7
    0.008M
     
    3
     
    8
    0.009M
     
    2.6
     
Finding the Diluted [IO3-]:  You will need to perform some dilution calculations to find out the diluted [IO3-]. Assume that the [IO3-] given is the concentration before any mixing occurs. As you may know, as soon as something is mixed with another solution, the total volume changes. This results in a new concentration for that particular substance. Note that solution “A” in the video is IO3- and let’s assume that there is 10mL of this initially. Solution “B” contains the bisulphate ions, acid and starch and let’s also assume that this is 10mL. Hence, the total volume is always at 20mL. Include what you have calculated in your data table and provide a sample calculation for ONE of your dilutions. (1 mark)
Finding the Rate: What is the rate of reaction for each dilution in M of KIO3/s? Assume that all of the KIO3 is consumed during the reaction. Include this data in your data table as well and provide a sample calculation for ONE of your dilutions. (note: the video calculated the rate as 1/s but for my assignment, please calculate the rate as M/s). Use the diluted concentration for your calculation. (1 mark)
3.  Looking at the graph and the data, what did you find the relationship to be between concentration and rate? (0.5 marks)
 
4. In the graph, notice how the line became flat from 0.005M to 0.006 M. Why do you think this may have been the case? (0.5 marks)
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NATURE OF REACTANTS ON RATE
5. Notice how Fe2+ reacted much faster than C2O42-. What do you think you can do to SLOW DOWN the rate of reaction of Fe2+? Please explain in detail how your method will slow down the reaction rate. No mark will be awarded without a valid explanation (1 mark)
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EFFECT OF TEMPERATURE ON RATE
6. Notice how the reaction rate vs [IO3-] graph was pretty much a straight line. From what you learned in the video and from the course notes, will you expect the reaction rate vs temperature graph to increase in a straight line as well? Please explain your answer. (1 mark)
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GENERAL QUESTIONS
7. In the following equation, N2(g)+3H2(g)↔ 2NH3(g) what are two ways you can measure the rate of reaction?(Be specific as possible. ie. what physical quantity are you going to monito
measure?) (1 mark )
 
8. What are the four factors that can affect reaction rate that we examined in this video? Explain how EACH of the factors can affect the reaction rate using the principle of collision theory. (4 mark )
 
9. Many industries seek ways to speed up reactions. How would the ability to increase the reaction rate be beneficial for these companies?  Also, based on what you have learned in this module, what do you think are some of the ways companies are speeding up reactions? (1 mark)
 
10. The equation for an overall reaction is:       I-  +   OCl-    →    IO-   +    Cl-
          a)  The following is a proposed mechanism for this reaction. One of the species has been left out and replaced with "?". Determine what that species is.  (0.5 marks)
 
Step 1:    OCl-   +    H2O    →     HOCl   +    OH-     ( fast )
Step 2:    I-    +  ?      →     IOH    +    Cl-       ( slow )
Step 3:     IOH    +    OH-    →IO-  +    H2O   ( fast )
         b)  Which species in the mechanism above acts as a catalyst? (0.5 marks)
          c)  Which three species in the mechanism above are intermediates?  (0.5 marks)
 
         d)  Step ______________ is the rate determining step. (0.5 marks)
 
11.  Review the “heats of reaction” section (p14) in Hebden and answer the following question using complete sentences. You may have seen athletes use cooling packs when they are injured. These are packs containing chemicals when mixed by ru
ing or shaking the pack containing the chemicals becomes cool like ice. Explain this observation using what you have learned in this module, particularly the section on heats of reaction. (Hint: start by writing out a general formula for this reaction A+B→AB etc. and try to add the heat term into the equation) At bare minimum, you should have the vocabulary endothermic or exothermic and positive enthalpy change or negative enthalpy change in your answer. (2 marks)
 
12.   What are some things you can do to slow down the rate of food spoiling? Please explain your answer using collision theory. (1 mark)
 
13.   Can a catalyst change an exothermic reaction into an endothermic reaction or vice versa? Please explain your answer. (1 mark)
 
14.  If a catalyst is removed from a reaction, what do you think will happen to the reaction? Will the reaction still keep on going? Please explain your answer (1 mark).