Ksp and the Common Ion Effect
I just completed a lab in which I titrated Calcium Iodate with Na2S2O3. During the titration we were told to add a starch once the liquid had turned light yellow. When we did this it became dark and we just had to titrate a few drops more. I'm writing the lab write up for this lab and was wondering why we had to add the starch and why the color changed so dramatically.