• Iodine Solution
Weigh 7.7g of potassium iodide into a 50cm3 beaker. Use distilled water to help the iodide dissolve. Swirl for a few minutes until the iodide has completely dissolved. Using a funnel to help, pour the potassium iodide into a 500cm3 volumetric flask, make sure all traces of the solution is in the volumetric flask. Using distilled water would be a good method in order to rinse the beaker. Make the solution up to the 500cm3 mark with iodine (1% concentration)
• Starch Indicator Solution
Weigh 0.25g of soluble starch and add it to 50cm3 of near boiling water in a 50cm3 beaker. Stir it in order to dissolve and wait for it to cool before using.
Procedure
Safety
• Before conducting the experiment, be sure to put on safety goggles and
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Using the equation of the titration in the experiment (Equation 1), calculate the number of moles of the ascorbic acid reacting.
4. Then proceed to calculating the concentration in mol. dm3 of the ascorbic acid in the solutions that was obtained.
Data Collection and Processing
Raw Data
Table 1: Amount of Iodine Reacting (± 0.05cm3) in the titration FT 1 FT 2 FT 3 FT 4 FT 5
Trial 1 1.9 1.8 1.8 1.5 1.6
Trial 2 2.1 1.8 1.7 1.5 1.6
Trial 3 2.1 2.0 1.8 1.5 1.5
Trial 4 2.5 2.3 1.7 1.6 1.5
Trial 5 1.9 1.8 1.6 1.6 1.4
Average 2.1 1.94 1.72 1.54 1.52
Analysis
The results of Table 1 are shown graphically in Figure 2 where the calculated and measured Iodine Solution are plotted with respect to the amount of days. The graph can be observed, showing that the measured value of the iodine is very close to the theoretical one. It can be seen that each time the Vitamin C is frozen, the iodine solution reacting with the Acid decreases. This means that the Ascorbic Acid is being destroyed every time it is frozen.
Volumetric Analysis
Calculating the moles of iodine reacting
Since the potassium iodide was mixed with the iodine to create triiodide so that the starch indicator could form the complex, it does not have to be