UNIT 01: Reaction Rates
BCLN CHEMISTRY 12 - Rev. July, 2015
Project: Iodine Clock Reaction Lab
Potential Credits:
Name: ________________
/15
Goal:
To further investigate the various factors that can affect reaction rate specifically: concentration and
temperature.
Instructions:
Begin by watching this video: Iodine Clock Reaction . You will see two different reactions. A slow
reaction in which Iodide ions are produced and a fast reaction in which in which the iodide ions are
used up. These two reactions combine to give the overall reaction.
Concentration Data and Observations:
1. Write the reaction equation for the first reaction you see in the video. It will appear above the
presenters head at the 44s mark of the video. Be aware there are some errors in terms of placement of
the charge. Do your best to correct these errors when you write the equation. For example the last
ion should be H+ not H+.
2. Write the reaction equation for the second reaction. It will appear at the 53s mark of the video.
3. Explain what happens when solution A (0.010M KIO3) is mixed with solution B (NaHSO3 made
from starch and H2SO4). This occurs at the 1:30 mark of the video
4. Fill in the table at the top of the page. The first 3 rows can be found at the 4:06 mark of the video.
The concentration of KIO3 can be calculated using a dilution calculation where the old [KIO3] is
always 0.010 M and the new volume is always 10 mL. The old volume will be the value from the top
row of the table.
New [KIO3 ] = Old [KIO3 ]x
Old Volume
New Volume
In this project we will be using inverse time as our rate. To calculate inverse time you simply do 1/time.
Example: 1 / 15.0s = 0.067 s-1
Page 1 of 4
UNIT 01: Reaction Rates
BCLN CHEMISTRY 12 - Rev. July, 2015
Table 1: Fill in these results by watching the video and doing the calculations shown on the previous page
Volume of KIO3 (mL)
10.0
9.0
7.0
5.0
3.0
Volume of water (mL)
0.0
1.0
3.0
5.0
7.0
Time for reaction
15.0
17.0
21.0
29.0
45.0
Concentration of KIO3 M
Rate [use inverse time (s-1)]
Concentration Graph:
Plot a graph of your results. Reaction Rate on the vertical axis and Concentration KIO3 on the
horizontal axis. This is best done in a program such as Microsoft Excel but can also be done on
graph paper by hand.
Page 2 of 4
UNIT 01: Reaction Rates
BCLN CHEMISTRY 12 - Rev. July, 2015
Concentration Questions:
1. Describe the general shape of your graph.
2. What is the rate of the reaction when the concentration is zero? Explain why this is.
3. Using collision theory, explain why increasing the concentration will increase the reaction rate.
Temperature Data and Observations:
1. The experiment was repeated with a wrinkle. Rather than changing the concentration, the
temperature was changed instead. Complete the table below.
Table 2: Fill in these results by calculating the rate the same way you did the rate for the concentration
section
Temperature (oC)
5.0
15.0
25.0
35.0
Time for reaction
115
58
29
15
Rate [use inverse time (s-1)]
Page 3 of 4
UNIT 01: Reaction Rates
BCLN CHEMISTRY 12 - Rev. July, 2015
Temperature Graph:
Plot a graph of your results. Reaction Rate on the vertical axis and Temperature on the horizontal
axis. This is best done in a program such as Microsoft Excel but can also be done on graph paper by
hand.
Temperature Questions:
1. Describe the general shape of your graph. Is it a straight line or a curve?
2. By what factor does the rate increase each time the temperature goes up 10 oC?
3. Using collision theory, explain why increasing the temperature will increase the reaction rate.
4. Why would changing the surface area of reactants have no effect on rate for this reacion?
Page 4 of 4