Iodine Clock Reaction Lab
Name: __________________ Date________________________
In this video you will see two different reactions: one in which iodine is produced (slow reaction) and one in which the iodine in the first reaction is used up (a fast reaction).
These two reactions make up the steps leading to the final reaction. In this lab you will be changing the concentration of reactants in Part 1 and temperature in Part 11 and determine their effect on the reaction rate.
Purpose : To observe and record the effect of changing the concentration and temperature on the rate of a reaction.
Procedure : As shown on video. Watch the video called Iodine clock reaction and record all observations and data.
Data and Observations
Part 1: Effect of Concentration
Write the first reaction that takes place in the lab?
Write the second reaction that takes place in the lab?
________________________________________________________________________
Explain what happens when solution A 0.010M KIO
3
is mixed with solution B NaHSO
3
(starch and H
2
SO
4
) for each volume of Solution A.
________________________________________________________________________
________________________________________________________________________
Table 1: Fill these results from watching the video
Volume of 10.0
KIO
3
(mL)
Volume of water (mL)
0.0
Time for reaction
Concentration of KIO
3
M
Rate [use inverse time
(s
-1
)]
0.010
0.067

Part 1 Questions
1.
Calculate the rate of the reaction (you will be using the reciprocal of time (in s
-1) to see the relationship between rate and concentration). Use dilution calculation to find the concentration of KIO
3.
The starting concentration of KIO
3
is 0.010M and the first calculation is done as example. Fill the answers in the table 1.
2.
Plot a graph of your results, with rate plotted against [KIO
3
].
3.
Explain what is happening on the graph.
________________________________________________________________
4.
Why does changing the concentration change the rate of the graph by referring to the collision theory (Read the collision theory if you have not done that section)?
_________________________________________________________________
Part 11 Effect of Temperature
Table 2
Temperature
0C
Time for reaction (s)
5.0
115
15.0
58
25.0
29
35.0
15
Rate: [use inverse time
(s
-1
)]
Questions Part 11
1.
Calculate the rate of reaction at each temperature (in s-1) by taking the reciprocal of the time elapsed. Fill table 2.
2.
Calculate the factor by which the rate changed for each 10
0
C interval in temperature.
__________________________________________________________
3.
Plot a graph of your results, with rate plotted against temperature.
4.
Explain why the change in temperature changes the rate of a reaction.
__________________________________________________________
5. Why does surface area not affect the rate of this reaction?
__________________________________________________________
Conclusion

State how the rate of a reaction is affected by a) altering the concentration of reactants and by b) altering the temperature.