Iodine Concentration
In order to prepare the iodine solution titrant, exactly 50 mL of 0.01 M KIO3, exactly 20 mL of 10% KI solution, and exactly 25 mL of 0.3 M H2SO4 was transferred into a 100 mL volumetric flask using a volumetric pipette. The volumetric flask was then filled to the mark with distilled water. The flask was covered with Parafilm and inverted to mix. The next part of the experiment was to determine the Vitamin C in a solution of known concentration. Observations of the Vitamin C sample and the amount found on the label was recorded. A tared piece of weighing paper was used to weigh 0.27 g of Vitamin C. The Vitamin C was then transferred to a clean 50 mL volumetric flask. The flask was filled to the mark with distilled water and covered with Parafilm. It was then inverted to mix.
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Exactly 10 mL of the Vitamin C solution was transferred to a clean 250 mL Erlenmeyer flask using a volumetric pipette. 5 mL of 0.3 M H2SO4 and 2 mL of 1% starch solution was added to the flask containing the Vitamin C solution and was swirled to mix. A regular pipette was used because a precise amount was not needed. The burette was conditioned using the iodine solution that was prepared in Part B of the experiment. The burette was conditioned by pouring the iodine solution through the entire burette making sure that the solution touched all of the sides.
The burette was then filled with the iodine solution and the initial reading was recorded. The iodine solution was used to titrate until the solution turned purple and stayed that color after the solution was swirled. The final burette reading was recorded to the 0.1 mL and the actual volume of iodine solution that was delivered to the flask was determined. The next part of the experiment was to determine the Vitamin C in a drink sample. Observations and the amount of Vitamin C found in the sample from the label were recorded. Exactly 50 mL of the drink sample was placed in a clean 250 mL Erlenmeyer flask using a volumetric pipette. 10 mL of 0.3 M H2SO4 and 2 mL of starch indicator solution were added to the flask using a regular pipette since a precise measurement was not required and the solution was swirled to mix. The initial burette reading was recorded to the 0.01 mL. The iodine solution was used to titrate until a gray color appeared and stayed after swirling. The final burette reading was recorded to the 0.01 mL and the actual volume was
determined.
Exactly 10 mL of the Vitamin C solution was transferred to a clean 250 mL Erlenmeyer flask using a volumetric pipette. 5 mL of 0.3 M H2SO4 and 2 mL of 1% starch solution was added to the flask containing the Vitamin C solution and was swirled to mix. A regular pipette was used because a precise amount was not needed. The burette was conditioned using the iodine solution that was prepared in Part B of the experiment. The burette was conditioned by pouring the iodine solution through the entire burette making sure that the solution touched all of the sides.
The burette was then filled with the iodine solution and the initial reading was recorded. The iodine solution was used to titrate until the solution turned purple and stayed that color after the solution was swirled. The final burette reading was recorded to the 0.1 mL and the actual volume of iodine solution that was delivered to the flask was determined. The next part of the experiment was to determine the Vitamin C in a drink sample. Observations and the amount of Vitamin C found in the sample from the label were recorded. Exactly 50 mL of the drink sample was placed in a clean 250 mL Erlenmeyer flask using a volumetric pipette. 10 mL of 0.3 M H2SO4 and 2 mL of starch indicator solution were added to the flask using a regular pipette since a precise measurement was not required and the solution was swirled to mix. The initial burette reading was recorded to the 0.01 mL. The iodine solution was used to titrate until a gray color appeared and stayed after swirling. The final burette reading was recorded to the 0.01 mL and the actual volume was
determined.