Which O.J> has the most Vit. C>?

Questions about "Which Orange Juice Has the Most Vitamin C?" project and kit. (http://www.sciencebuddies.org/science-f ... l?from=AAE)

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Which O.J> has the most Vit. C>?

I have a 10%Potassium iodide 5% Iodine ,Lugol's solution. How do I dilute it to be compatible with the project ; Which orange juice has the most Vit. C. The experiment does not state what concentration of Lugol's solution do they start with. I already did the experiment with diluted Lugol's solution(1.8% Iodine and #.3.0% Potassium iodide) 30 mL. I diluted it with 300mL as stated in the experiment. I did not get the results as stated. Should I buy another bottle of the Lugol"\'s solution ,and not dilute it,since on the bottle states that it is IODINE DiluteLugol's solution? Can I dilute the other Lugol's solution the 5% and 10%,but I do not know how? I need Help . Thanks. Halina.
Halina

Posts: 2
Joined: Wed Oct 10, 2012 6:04 am
Occupation: Dentist
Project Question: Titration of vit.C.
Project Due Date: Nov,1
Project Status: I am conducting my experiment

Re: Which O.J> has the most Vit. C>?

Hi Halina,

This sounds like a really great project. I want to make sure I understand what you have already tried. In your first attempt you started with 30 mL of a solution that had 1.8% iodine? Then you added water until you had a final volume of 300 mL? If this is what you did then you would end with a solution that has 0.18% iodine. This is pretty close to the amount that I have used in this experiment in the past.

What results did you get exactly? So you made a standard vitamin C solution that had a concentration of 1mg/mL. Then you used 25 mL of that solution so you had 25 mg of vitamin C in total. Then you titrated that with your diluted iodine solution. How much iodine did you add until you saw the color change? The numbers that were given at the end of the protocol were made up. So if you didn't get the same numbers don't worry.

If you want to use your 10%Potassium iodide 5% Iodine ,Lugol's solution here is how I would dilute it:

-Measure 10 mL of the 10%Potassium iodide 5% Iodine ,Lugol's solution with your 50 mL graduated cylinder
-Pour the 10 mL into the 500 mL graduated cylinder.
-Add water to the 500 mL graduated cylinder until you have 300 mL of liquid.
-Now use this dilute solution to titrate your samples.

Let me know if you have anymore questions.
Kierstyn
microkts
Expert

Posts: 67
Joined: Thu Oct 20, 2011 7:24 am
Project Question: n/a
Project Due Date: n/a
Project Status: Not applicable

Re: Which O.J> has the most Vit. C>?

Thank you for your reply. I will try your suggestions , and let you know the results.
Halina

Posts: 2
Joined: Wed Oct 10, 2012 6:04 am
Occupation: Dentist
Project Question: Titration of vit.C.
Project Due Date: Nov,1
Project Status: I am conducting my experiment