Kinetics of the Reaction between Acetone and Iodine
The key aim of this experiment was to determine the rate equation for the acid-catalysed iodination of acetone and to hence consider the insinuations of the mechanism of the rate equation obtained.
The stoichiometric equation for the reaction between iodine and acetone is below, followed by the rate equation (where x,y,z and k are the values to be obtained): I2 + CH3COCH3 CH3COCH2I + HI
-d[I2]/dt = k [I2]x [CH3COCH3]y [H+]z
The procedure was performed as follows: For run 1, 20cm3 of acetone, 10cm3 of sulphuric acid and 145cm3 of water was added to a conical flask. 25cm3 of iodine was then added to this solution which started the reaction and immediately, 20cm3 samples of this mixture was added to six flasks. After successive 5 minute intervals, sodium acetate was added to each of the conical flasks in order to stop the reaction. Flask 1 and 2 were then titrated, (3 to 6 turned colourless) using 0.01M sodium thiosulfate and a starch indicator. Care was taken here to put the starch in when before an irreversible black/blue complex arised. This reaction gave the order for iodine. In order to find the order for acetone, the same procedure was adopted but with 10cm3 of acetone instead of 20cm3 and 155cm3 to keep the same total reaction volume. In order to find the order for H+, the procedure was repeated but 5cm3 of sulphuric acid was used instead of 10cm3 and again 150cm3 of water was used to keep the total volume constant. The amount of iodine added remained unchanged.
The results for each titration for each run are shown below, followed by their respective graphs:
|RUN 1 | Time (mins) |
| |5 |10 |
|Flask: |1 |2 |
|Titre: |5.80 |4.40 |
|RUN 2 | Time (mins)...
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