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Name: Nan
Status: student
Age: 14
Location: N/A
Country: N/A
Date: 8/18/2003
Question:
I am working with Vitamin C and how to find Vitamin C by a solution. The solution is the cornstarch and water mix together; and add iodine (it turns purple). When a Vitamin C tablet is added, the solution turned clear. I would like to know that why and how the solution turn from purple to clear? Thank you very much!

Replies:
When iodine is added to the starch solution, the I3(-1) ion forms a complex with the starch that is a deep purple, as you observed. Vitamin C is a reducing agent. So it reacts with the iodine complex to produce I(-1) which is colorless.

Vince Calder


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