Determing Molarity. Did I do it right?

[Raheelp]

The questions asks us to: Determine the molar concentration of I- in a reaction mixture. The reaction was as follows (data):

20 mL of .1 M KI
0 mL of .1 M KCl
10 mL of .003 M Thiosulfate
20 mL of .10 M Persulfate

I did the following:

20 ml I- x (1 L / 1000 mL) = .02 L I-

.02 L I- x (.1 mol / 1 L) = .002 mol I-

.002 mol / .05 L solution (20 mL + 0 mL + 10 mL + 20 mL) = .04 M I-

Little rusty, wanted to make sure I did this right.

Any help will be greatly appreciated!

[Borek]

Question is ambiguous. Does it ask for initial concentration, or for concentration after reaction took place?

Initial looks OK to me.

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[Raheelp]

k, going with it heh. I do believe it is initial because we have no post-reaction data.

[Borek]

Well, you may calculate post reaction from stoichiometry.

I have not checked, but could be final concentration of I- is identical to initial.

--
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pH calculator (http://www.chembuddy.com/?left=BATE&right=pH-calculator), stoichiometry calculator (http://www.chembuddy.com/?left=EBAS&right=equation-balancing-stoichiometry)