[Milla]

Maybe someone can help me with this week's lab.. eek!! My TA is never available to help.

We were to titrate 1.7g of KIO₃ in Na₂S₂O₃ solution. Added the excess I with KI, starch, HCl, etc. Then we had to find the M of K₂S₂O₃ with this information. HOW?!

The second part, we titraded 10mL of Ca(IO₃)₂ in the same Na₂S₂O₃ solution. Added the KI, starch, HCl once again. We need to find the M of IO₃^- and the solubility of it, so we can calculate the Ksp of Ca(IO₃)₂ using all this information. HOW?!

I'm having a hard time seeing how all of this falls into place. I can get through Organic no problem, but I stumble through regular chemistry lab  

All, and any, help would be greatly appreciate it.
~Milla

[Borek]

IO3(-) + I- -> I2 + H2O

I2 + S2O3(2-) -> S4O6(2-) + I-

Unbalanced, but you should get the general idea.

[AWK]

For Ksp calculation you should work with a saturated solution. This information is missing.