Vitamin C is an essential nutrient that supports immune health and wound healing. The document describes how to perform a titration to determine the amount of vitamin C in foods. A titration involves adding iodine solution dropwise to a juice or food sample along with a starch indicator. The amount of iodine solution needed to cause a color change indicates the vitamin C concentration, allowing comparison to daily recommended intakes and analysis of different foods' contributions.

2.  Essential nutrient for humans
 Healthy immune system
 Antioxidant
 Wound healing
 Water soluble:
needs to be replenished daily

3. To determine the amount of Vitamin C in
different foods
Recommended Daily Intake
 Boys 14–18 years 75 mg
 Girls 14–18 years 65 mg

4.  Titration is used to determine the
concentration of an unknown solution
 We will be using titration to determine the
amount of vitamin C in various foods
 How is a titration performed?

5. Juice containing
Vitamin C
Starch solution
used as indicator

6.  Add iodine solution
drop by drop into the
flask containing the
juice/starch solution
 When the solution
changes color, stop
adding iodine
 Determine the volume
of iodine used for the
titration
Burette
filled with
iodine
solution

7.  Indicates presence
of iodine
 No Vitamin C left
Amount of
iodine
solution
needed to
titrate the
Vitamin CStarch
Indicator turns
purple/black

8.  C6H8O6 + I3
- + H2O  C6H6O6 + 3I- + 2H+
 In the presence of Vitamin C (C6H8O6), the
iodide ion (I-) is produced
 Iodide does not react with starch  no color
change
 When there is no more Vitamin C left, the
iodine will no longer react to produce iodide
 The solution will turn purple, indicating the
presence of iodine
Vitamin C colorless

9.  No change in solution color: Vitamin C is
present
 Purple/Black solution: All Vitamin C has
reacted

10.  We will begin the experiment with a known
concentration of Vitamin C to standardize
our measurements
 For example, 10ml of iodine solution was
used to titrate the standard vitamin C
solution with 0.25g of Vitamin C

11.  Once we know how much iodine solution it
takes to titrate our known concentration of
Vitamin C,
 We can experiment with other foods to find
out how much vitamin C they have
10ml of Iodine solution
0.25g Vitamin C
=
6ml of Iodine solution
? g Vitamin C
VS.

12.  The more iodine solution needed for the
titration, the more Vitamin C is contained in the
food
 We can use this to estimate how much Vitamin C
we are getting in our diet and if we are meeting
the nutritional recommendations!

13.  Why are we performing a titration?
 Why do we need vitamin C daily?
 What foods could we test for vitamin C in our
experiment?
 Do you think that you are getting enough
vitamin C in your diet? Why?
 What are the side effects of having an
insufficient amount of vitamin C in a diet?