Vitamin C in Juice - Help

[Not a Scientist]

My daughter is in 3rd grade. Her science project is to determine which juices have the most Vitamin C. We performed the project by adding different juices to the iodine mixture, but it took over 100 drops of each juice to make the blue/purple color completely disappear. Does anyone know if this is correct? I was expecting to only need a few drops. I may have done something wrong.

 

Thanks.

[freeztar]

How many drops of ioding are you using? Are you stirring while adding?

[Not a Scientist]

The instructions were to mix 2 Tbs corn starch with 1 cup water. Add 4 drops of iodine. Then we placed 2 Tbs of the mixture into 6 glasses. Next add the juice, one drop at a time, swirling the liquid after each ten drops, until the liqid was colorless.

[freeztar]

The instructions were to mix 2 Tbs corn starch with 1 cup water. Add 4 drops of iodine. Then we placed 2 Tbs of the mixture into 6 glasses. Next add the juice, one drop at a time, swirling the liquid after each ten drops, until the liqid was colorless.

 

If you cut those quantities in half (or quarter), you will need a lot less drops. You might also consider a more accurate measure than tbsp. Do you have a graduated cylinder?