, Connor Dennis, Josh Istas
7:30-10:20 October 19, 2006
Vitamins, or micronutrients, are needed to stay alive.
For example, Vitamin C is
responsible for the synthesis of collagens.
If people do not eat or obtain enough Vitamin
C, they will develop scurvy, a disease that causes the loss of connective tissue causing
hair loss, lesions, tooth loss, etc.
Vitamin C, ascorbic acid, is found abundantly in fruits and vegetables.
apple a day may not keep the doctor away, but it can help to fight against scurvy.
In the lab, a titration between iodine and ascorbic acid occurs.
The following is the
balance equation for the reaction:
Starch was added to the ascorbic acid solution as an indicator.
When the solution reached
its equilibrium point, the solution turned to a dark blue color.
First, the burette was setup.
Then, about 50 mL of iodine was added to the burette.
25.0 mg of ascorbic acid and 25.0 mL of distilled water were added into a volumetric
Then, 20 drops of 0.2 M ascetic acid were added into the flask.
Next, 30 drops of
2% starch solution to the flask.
The solution was mixed.
The starting volume in the
burette was measured.
Then, the iodine solution was added slowly to the ascorbic acid
solution until it changed to a dark blue color.
The ending volume in the burette was
measured to find out how much iodine was needed to reach equilibrium.