[shuyak]

A saturated solution of Ca(IO3)2 was prepared and filtered. A 25.00-mL sample of the filtrate was titrated as outlined in this experiment, and 19.75 mL of 0.1086 M Na2S2O3 were required to reach the end point.


   How many moles of I2 were titrated?
              I figured 1 mol of 2 divided by 2 moles of S2O3 and multiplied it by the moles of sodium

    How many moles of IO  were present in the sample solution?
              i did get .000357 mol but am not sure if i am right

    How many moles of Ca2+ were present in the sample solution?
              i also got .0007 mol for this and am not sure if i am right

    Calculate Ksp for Ca(IO3)2.
              i know that the formula for this one is Ksp= [Ca2+][IO-(little3)]2, i am not sure what else to do

[Borek]

Please read forum rules.

You just don't ask. You try, you tell us what you did, we push you in the right direction.

[shuyak]

i edited it, sorry...i entered the questions but forgot to add how far i got in the problems.

[Borek]

Write equations of reactions taking place.

[shuyak]

Ca(IO3)2(s) --> Ca2+(aq) + 2IO-(little 3)(aq)

and

Ca2+(aq) + 2IO-(little 3)(aq) --> Ca(IO3)2(s)

[Borek]

That's not all - where does iodine come from? How does it react with thiosulfate?

[UG]

How does it react with thiosulfate?

Am I allowed to answer this? 

Well, here it goes anyway.

I₂ + 2S₂O₃^2-  2I^- + S₄O₆^2-

[Borek]

Am I allowed to answer this?

It would be better if the OP will try to do the question by her/himself.

[UG]

Okay Borek.

[Arkcon]

How does it react with thiosulfate?

Am I allowed to answer this? 

Well, here it goes anyway.

I₂ + 2S₂O₃^2-  2I^- + S₄O₆^2-

All members of this forum are allowed to give as much, or as little info as they want to.  We generaly try to give useful hints, so that students try to reason out the answer for themselves, and "Citizen Chemists" learn to check primary sources (college level texts, for example) to learn the basics. 

If you give too much away, lazy people will be back, often, demanding complete answers, angrily.  And I've noticed, people who give complete answers, don't tend to come back.  It just gets tiring, after a while.  Whereas, I've found, figuring out new ways to give subtle hints is a challenging puzzle in and of itself.

[UG]

Okay, thanks for the tips. 
I'll keep that in mind next time.
I know exactly what you mean when you say: lazy people will be back, often, demanding complete answers, angrily.