This experiment consists of
two parts. In the first portion of the experiment,
the students will be standardizing the base.
In the second part of the experiment, the students
will use the base, which was previously standardized
to titrate vitamin C, which contains ascorbic
acid. The percentage of ascorbic acid in the
vitamin C sample will then be determined.
* Two 50 mL burettes
* Three 250 mL Erlenmeyer flasks
* 10, 50 and 250 mL graduated cylinders
* Storage container
* Stirring rod
* Oxalic Acid
* Milk of magnesia
* Phenolphthalein indicator
* Distilled water
* Vitamin C
PART I: Standardization of Milk of Magnesia
Weigh out 1.5 g of oxalic acid and place it
into a volumetric flask and then dilute to 100
mL with distilled water. Dispense 20 mL of this
solution into an Erlenmeyer flask and add 3
drops of phenolphthalein indicator to the flask.
Prepare a solution of milk of magnesia by diluting
17 mL to 200 mL using distilled water. Titrate
the 20 mL oxalic acid sample with the milk of
magnesia solution to the end point.
After completing three titrations of oxalic
acid samples, calculate the average molarity
of the milk of magnesia solution.
PART II: Determination of the Percent of Ascorbic
Acid in Vitamin C
Weigh 2 100 mg tablets of vitamin C. These
tablets are then to be crushed and dissolved
in 100 mL of distilled water. Take 7 mL of the
milk of magnesia solution previously prepared
and dilute to 100 mL with distilled water. Fill
a clean 50 mL burette with this solution. Dispense
20 mL of the vitamin C solution into a 250 mL
Erlenmeyer flask and add 3 drops of phenolphthalein
indicator. Titrate the milk of magnesia sample
with the vitamin C solution.
After completing three titrations of the milk
of magnesia sample, calculate the average molarity
of the vitamin C sample and then determined
the percentage of ascorbic acid in the vitamin