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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: ryans122 on October 19, 2017, 01:41:28 AM

Title: How to find the vitamin C content of orange juice?
Post by: ryans122 on October 19, 2017, 01:41:28 AM

I'm an IB chemistry SL student doing an IA on the vitamin C concentration of orange juice. We haven't learned about the titration process, so here is what I have done so far:

5KI + KIO3 + 3H2SO4 -> 3I2+ 3K2SO4 + 3H2O

This is the equation for producing the iodine solution. Now using a titration process, I added the iodine solution to the orange juice. I measured the volume of Iodine solution used.

Here is the formula for the reaction between the vitamin C and the Iodine solution.

C6H8O6 + I3- + H2O → C6H6O6 + 3I- + 2H+

I'm not sure where the Triiodide comes from. In the Iodine solution, we have Iodine, but the next reaction requires triiodide. Can someone explain this to me? I'm not a very good chemistry student.

Title: Re: How to find the vitamin C content of orange juice?
Post by: Borek on October 19, 2017, 03:34:29 AM

Just googling for triiodide should quickly lead you to an answer.

Title: Re: How to find the vitamin C content of orange juice?
Post by: ryans122 on October 19, 2017, 05:26:52 AM

Quote from: Borek on October 19, 2017, 03:34:29 AM

Just googling for triiodide should quickly lead you to an answer.

I have, but I've gotten something along the lines of the Iodine being more soluble. I don't understand how the Iodine somehow changed to the triiodide.

Title: Re: How to find the vitamin C content of orange juice?
Post by: Borek on October 19, 2017, 07:32:13 AM

Quote from: ryans122 on October 19, 2017, 05:26:52 AM

I have, but I've gotten something along the lines of the Iodine being more soluble.

Increased solubility is a final effect, yes.

Quote

I don't understand how the Iodine somehow changed to the triiodide.

Have you read the wikipedia article on triiodide? It contains reaction equation that explains what is going on.