Need Chemistry Help badly!

[geekgrl]

Ugh. Get over a strep throat and you have tons of makeup work.

I'm having trouble doing this concentration thing, so I thought I'd try here and see if anyone knows!

I have .2 molar KI and 19.75 mL of it.
I have .005 molar Na2S2O3 and 5 mL of that.
.1 molar K2S2O8 and 19.92 mL.
and 5 mL of water.

Now, I'm trying to find the molarity or concentration of:
S2O8^2-

I tried to take .1 M*19.92 / sum of all volumes in mL
and my TA has told me it's wrong.
I can't figure any other way????

[pickel]

Take 6 oz of orange juice
2 oz Vodka
1 oz Galliano liquer
Tall glass of ice
Blend and ingest

Repeat and you'll won't worry about the tons of makeup work

[geekgrl]

LOL that's true

I made the mistake of asking help on a chemistry board. I got "GO READ YOUR TEXTBOOK!"
And I have read my textbook 32905895 times.. and I'm still getting wrong answers.

[Gomer]

32905896th time is the charm =)

*grin* couldn't resist, not my area of expertise tho

[Warthog]

hmm...dang...where's Ch**co when you need him?

Good luck geekgrl....I hate science with a passion so of course I'm no help

Warthog

[TheBurningCat]

LOL is chooco a swear word now wart?

Will i get banned for calling someone a chooco?

Anyway sorry geekgrl, science annoys me

[sven222]

geekgirl: When you say you want the concentration of the S2O8^2- ion, is that before the reaction takes place or after?

If before, all you need to do is find the percentage composition of S2O8^2- in K2S2O8, then use that figure to find the percentage of the amount of S2O8^2- in K2S2O8, then with that number you calculate the concentration.

[geekgrl]

Sven... I've been attempting to just do C1V1=C2V2

?

Anyway, I called my TA up and told him to meet me at the Chemistry Library today... I need some serious help. He tells me I am wrong, but I think I'm right.....


Oh, and why so many haters of science??? It can be cool when you aren't doing stupid lab reports!

[Gomer]

Go Science!

[BobOmega]

if this was back in time a year i might have been able to help. i remember doing this is chem. i'm sure when i start chem 2 next semistar (arrrggg can't belive i signed up for it) allthough i could look in my notes and see if i can figure it out. oh wait this may be more complex then what i did. sorry i doubt that what i learned would help any if not confuse you even more. we only did kinda basic concentrations. or at least i think so.. sorry