powerpoint for fair

1. Google Science Fair Entry By Eduard Kenedi

2. Introduction
This is a PowerPoint that will explain my question that
was submitted to the Google Science Fair. The project I
chose was from the Chemistry branch of Science. It
included iodine titration to find the amount of Vitamin
C in different Orange juices. The presentation will take
you on a step by step guide through my chosen
experiment.

3. Question and Hypothesis
The question chosen was : Which type of Orange juice
(fresh or bottled) has the most Vitamin C and is most
cost-efficient.
The hypothesis was that the freshly squeezed orange
juice will have more Vitamin C than the bottled one.
Sadly the fresh juice is also more costly.

4. Apparatus needed
 Samples of two different kinds of orange juice:
 home-made fresh-squeezed (which means you'll need to buy some
oranges),
 premium not-from-concentrate juice (e.g. Cappy ® Tropicana® or
Florida's Natural®),
 Juicer for extracting juice from oranges (manual or electric is fine)
 Cheesecloth
 Vitamin C tablets
 Distilled water
 Masking tape
 Permanent marker
 Small funnel (do not use for food after using it for chemistry)
 Iodine solution, use one of the following:
 Lugol's iodine solution, 50 mL or
 iodine solution for starch test

5. Apparatus needed (continued)
 Soluble starch, 10 g
 50 mL graduated cylinder
 500 mL graduated cylinder
 50 mL Ehrlenmeyer flask
 50 mL buret
 Ring stand
 Buret clamp
 Plastic transfer pipettes (or eyedropper) for adding drops of
starch indicator solution
 1/4 teaspoon measuring spoon, or an electronic kitchen balance
(accurate to 0.1 g)
 Glass jars for iodine (300 mL) and starch solutions

6. The Method
 The Lugol`s solution was diluted 1:10 in distilled water to make the iodine titration solution.
 30ml of Lugol`s solution was poured into the 500ml cylinder
 Enough distilled water was added to until the total volume was 300ml
 The solution was stored in a dry, light protected place.
 A starch solution was made.
 It could be anything between 0.5%-1.0%, although it was not critical.
 With 1.0% add 1g of the soluble starch to 200ml of near-boiling water.
 Stir and dissolve, let cool.
 Leave in a dry, away from sunlight area.
 Make standard solutions of vitamin C.
 This will be used to standardize the iodine titrate.
 250g of vitamin C were crushed and diluted in 100ml of distilled water.
 Distilled water was added until the total volume was 250ml.
 25ml of Vitamin C standard solution were titrated.
 20ml of standard vitamin C solution was measured.
 This was poured into a 50ml Ehrlenmeyer flask.
 10 drops of Starch indicator solution were added.
 The 50ml buret was set up on the ringstand.
 The buret was filled with iodine titration solution using a funnel.
 The initial volume of solution in the buret was recorded.
 The Ehrlenmeyer flask was placed under the buret.
 The iodine titration solution was added drop by drop.
 The flask was swirled after each added drop.
 The titration was complete when the iodine titration solution created a blue-black color that lasted longer than 20 seconds.
 The final volume of iodine solution left in the buret was recorded.
 The amount of iodine titration solution needed to oxidize the Vitamin C was found by calculating the difference between the two
volumes.
 The results should agree with about 0.1 ml.

7. The Method (continued)
 The fresh orange juice was prepared.
 The juice of two oranges was squeezed using a juicer.
 The orange juice was filtered of seeds and pulp using filter paper.
 The titration of the fresh orange juice.
 20ml of fresh orange juice were measured.
 The juice was poured into an Ehrlenmeyer flask.
 10 drops of indicator solution were added.
 The 50ml buret was set up on the ringstand.
 The buret was filled with the iodine titration solution.
 The initial volume of iodine solution was recorded.
 The Ehrlenmeyer flask was placed under the buret.
 The iodine titration solution was added drop by drop.
 After every addition of iodine solution the flask was swirled.
 The endpoint was reached when the juice changed to a brownish color.
 The final volume of the buret was recorded.
 The amount of iodine titration solution needed to oxidize the vitamin C was calculated by finding the difference between
the two recorded volumes.
 The results should agree with about 0.1ml.
 The process above was repeated with each type of juice (fresh, bottled).
 The amount of vitamin C was calculated using a proportion (with made up numbers).
 It took an average of 8.5ml of iodine titration solution to titrate 20ml of 1mg/ml vitamin C standard solution. That meant
20mg of vitamin C in total.
 It took an average of 6.8ml of iodine solution to titrate 20ml of fresh orange juice.
 The amount of vitamin C in the orange juice was called X. X was found using the following equation: X = (6.8mg/ml) ×
(20mg) ÷ (8.5ml) = 16.0mg

8. Results and Calculations
Type of juice Amount of Iodine Amount of juice used
needed to titrate (ml)
Vitamin C Solution 1.0 0.25 g
Fresh Orange Juice 1.0 25ml
Cappy Juice 2.45 25ml
It took 1.0ml of Iodine to titrate 0.25 g of Vitamin C.
The Cappy juice took 2.45 ml of iodine to be titrated.
So:
1.0ml÷0.25g= 2.45÷X
4X=2.45
X=1.633 this is the amount of Vitamin C in the Cappy Juice
This value can now be converted to g/Liter:
1.633÷25=6.532g/L
The Fresh Juice took 1.0ml to be titrated and following the equation above:
4X=1.0
X=0.25 This is the amount of Vitamin C in the Fresh Orange Juice
The value above can be converted into g/Liters
0.25÷25= 10g/L of Vitamin C

9. Conclusion
In conclusion, the hypothesis was proven true. The fresh
orange juice had as much Vitamin C in it as the tablets
that had been diluted in water. The fresh juice had 10g/L
of Vitamin C whilst the bottled juice only had 6.532 g/L.
This shows that it is much healthier to drink freshly
squeezed orange juice than the bottled one. It also shows
that the bottled juice doesn`t put the exact amount of
Vitamin C included onto the bottle. Sadly, the bottled
juice is much cheaper and thus, more bought.

10. Bibliography and Thanks
 Here is a list of all sources used in the experiment:
 http://www.sciencebuddies.org/science-fair-
projects/project_ideas/Chem_p044.shtml?fave=no&isb=cmlkOj
E0NDEwNDU5LHNpZDoxLHA6MQ&from=TSW – as the idea
behind the project
 http://en.wikipedia.org/wiki/Titration and
http://en.wikipedia.org/wiki/Stoichiometry were used to give
explanations of unknown terms.
 Special Thanks to:
 My Science Teacher Ms. Holmes for supporting me in the
experiment.
 My parents, for buying and making the juices.
 The Technician Mr. Szilard for helping me obtain all the items
needed for the experiment.