UNIVERSITY COLLEGE OF ENGINEERING AND TECHNOLOGY MALAYSIA
Chemical Reaction Engineering Laboratory I
BKF2741
Chemical Reaction Engineering Laboratory I BKF2741
IODINE REACTION OBJECTIVEThe objectives of this experiment are
to:1. calculate the order of reaction, rate constant and activation
energy
2. study the effect of temperature towards the reaction rate
constantINTRODUCTION
In this particular experiment, the kinetics of ionic reaction is
investigated. The reaction are as follows;
(1)To get the concentration versus time of reaction data, these
chemical equations will be employed;
(2)
(3)I2 is released in the first reaction and used immediately in
second equation. The iodine ions in the first reaction is converted
into molecules in the second reaction. So, as far as the Na2S2O3 is
formed, the I- still exist and the overall I2 molecules are not
fully released.
Assume that rate of reaction for this equation;
(4) Thus, the rate of reaction is as follow;
[1]Assume that k is the dependent on the temperature. Thus, by
applying Arrhenius equation given;
[2]To get the kinetic projection, the values for n, m, A and E
constant must be calculated.
In order to get these values, 3 particular reactions mentioned;
i.e; Iodine Reaction I, II and III are carried out.
Iodine Reaction I- n order correlates with [S2O82-]
Iodine Reaction II-m order correlates with [I-]
Thus, the values of and m are determined.
Iodine Reaction III
Repeat the experiment by varying the temperatures. As the values
for n and m have been obtained from iodine reaction I and II, the
values of k for each reaction can be acquired. From the Arrhenius
relation, the values for A and E can be found out.PROCEDURE
Iodine Reaction I
1. Clean all the apparatus with distilled water
2. Fill 10 ml of K2S2O8 solution into the conical flasks and
placed them in water bath with 30oC 40oC water temperature. Wait
until the solution temperature reaches the waterbath
temperature.
3. Fill in 30ml of KI solution into another clean conical
flask.4. Fill Na2S2O3, starch solution and distilled water as in
what has been written in the procedure table into the prepared KI
solution.
5. Placed the mixed solutions (4) into the waterbath at
temperature 30oC 40oC. Stir the solution with magnetic stirrer and
hold until the temperature to reach the same temperature with the
waterbath temperature.
6. As the K2S2O8 solution reaches the same temperature with the
waterbath temperature, pipette the solution into the mixed solution
prepared before. Start to time when the solutions start to
mix/touch. Stir the solution with a magnetic stirrer and stop
timing once the solution colour change to purple (means the I2 has
formed).
7. Repeat steps 3 to 5 for different portion of Na2S2O3 and
distilled water volumes.
Note : Make sure all the apparatus are clean, especially the
pipette. The uncleanness of the apparatus leads to error of
experimental values.
Iodine Reaction II
The procedures are as in Iodine Reaction I except the value of
the solution. Please refer to data collection table 2.Iodine
Reaction III
The procedures are as in Iodine Reaction II except the
experiments is carried out at different temperatures as shown in
Table 3. The volume of each solution is fixed as follow:
5 ml of starch solution
10ml of Na2S2O35ml of distilled water
25ml K2S2O8.
DATA COLLECTIONS
Table 1. Iodine Reaction I Data Collections
MaterialVolume (ml)
Starch Solution555555
Na2S2O351015203040
KI303030303030
Distilled water555045403020
K2S2O8101010101010
Total105105105105105105
Time (min)
Mol K2S2O8 reacted
K2S2O8 concentration (M)
Table 2. Iodine Reaction II Data Collection
MaterialVolume (ml)
Starch Solution555555
Na2S2O3101010101010
KI51015203040
Distilled water555045403020
K2S2O8252525252525
Total100100100100100100
Time (min)
Mol K2S2O8 reacted
K2S2O8 concentration (M)
Table 3. Iodine Reaction III Data Gathering
NumberTemperature (oC)Time (min)
135
240
345
450
555
660
QUESTIONS1. Discuss how the experiment can be improved. 2. From
the results obtained, identify the overall order of reaction for
the reactions involved in this experiment. 3. From experiment
Iodine I and II, discuss the effect of temperature toward the
reaction constant, k.
Concentration of SolutionUse these solutions;
K2S2O8 W/V = 25.0g/l
KI
W/V=50.0g/l
Starch solution = 1%
W/V = 1g ( 100 ml (W/V =
Mass/Volume)___________________________________________________________________________________
Faculty of Chemical & Natural Resources Engineering, UMPPAGE
___________________________________________________________________________________
Faculty of Chemical & Natural Resources Engineering, UMP
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