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Topic: titration of vitamin c with starch indicator  (Read 3892 times)

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Offline futureengineer

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titration of vitamin c with starch indicator
« on: December 11, 2011, 10:37:07 PM »
 While doing my titration I was adding iodine solution to my vitamin c starch indicator solution and after adding 21 units it turned from clear to yellow. Was this the endpoint?  I thought it was supposed to turn bluish black.
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Offline UG

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Re: titration of vitamin c with starch indicator
« Reply #1 on: December 11, 2011, 10:39:55 PM »
Did you add the starch indicator?
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Offline futureengineer

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Re: titration of vitamin c with starch indicator
« Reply #2 on: December 12, 2011, 09:34:43 AM »
Yes, At least I think I did.  Could it be that I didn't have enough? I used 20 ml of vitamin c solution and 10 drops of starch indicator.  The starch indicator was made with 1/4 teaspoon starch and 200ml of water.
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Offline UG

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Re: titration of vitamin c with starch indicator
« Reply #3 on: December 12, 2011, 06:06:41 PM »
Wikipedia quotes a standard starch solution is made from 3g of soluble starch in 1 L of heated water, does that sound close to what you did?
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Offline futureengineer

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Re: titration of vitamin c with starch indicator
« Reply #4 on: December 12, 2011, 10:24:57 PM »
Yes, I used 1 gram per 200 ml of warm water.  That would be 5 grams in a liter wouldn't it?  That should have been plenty of starch.  I wonder if I need to add more than 10 drops into my vitamin c solution.  ???
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Offline Borek

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Re: titration of vitamin c with starch indicator
« Reply #5 on: December 13, 2011, 02:44:20 AM »
http://www.titrations.info/iodometric-titration-Vitamin-C

Procedures I know call for much more starch solution (of a comparable concentration).
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