[joy35]

I really really really need help
I did an open-ended investigation for chemistry. It was a redox reaction and i was supposed to titrate sodium thiosulfate (Na2S2O3) against iodine solution (KI3) using starch as my indicator - i put it with my primary standard sodium thiosulfate. It was a redox titration and the sodium thiosulfate didn't change color i think it was because it was too dilute cause i used 0.1 mol only and 20mL from this 0.1mol solution.
Because it didn't change color i paniced and added sulphuric acid (Na2SO4). In the end I decided to only use 1mL of Na2S2O3 but i still put in 10 drops (0.05mL) of H2SO4, it took 29.5mL of KI3 for it to change color. My only problem is i don't know the stoichiometry and how to write a reaction for this cause i don't know the products. I'm supposed to work out how much iodine solution there is. Do you know how?
the reaction is supposed to look like this:
KI3 + 2S203 -> 3I + S4O6
but i have no idea what it will be with H2SO4 with my reactants...
Do you know? I'm hoping the H2SO4 doesn't take part in the reaction or doesn't do anything to the reaction, so i can keep my formulas the same

Edit by Borek: color removed, my eyes hurt from formatting abuse.

[Borek]

http://www.titrations.info/iodometric-titration