Vitamin C startch AND ethanoic acid

becky_scotland · Post by **becky_scotland** » Tue Dec 12, 2006 11:32 am

Now this is a new question! I have just got the answer as to why one adds startch indicator near the end of the titration of iodine and ascorbic acid, and now I am wondering why i was advised to add Ethanoic acid at the start.I was told it would make my end point clearer.I can only think that the titration works better with the additionly hydrogen ions in the reaction. Anyone got any ideas!? thanks for any replies

carolinethorn · Post by **carolinethorn** » Tue Dec 12, 2006 12:00 pm

Hi Becky,

You figured it out for yoursefl already -
If you go back to that very good but slightly complicated text that Louise posted on your other question it includes this "iodometric titrations are carried out in strongly acid media, a situation that promotes the reaction between oxidizing agents and iodide." That would support your idea that additional hydrogen ions make the titration work better since it would promote the reaction between the vitamn C/oxidizing agent and the iodide.

Well done,
Caroline