[daistheputridone]

what is the concentration(molarity) of iodine in .130 molar potassium iodide

iodine's molar mass is 78.25% of that compound, so should it be 78.25% of that molarity, i.e 78.25% of .130?, making it .1017 mols/L

or is that not right?

either way input is appreciated

[renge ishyo]

If you start with .130 mol/L of KI then after complete dissociation you would have .130 mol/L of K⁺ and .130 mol/L of I^-. Now if they had given you .130 *grams*/L of KI then you might have to do an approach like you wrote (the easiness of the mol concept is why Chemists use it  .

[daistheputridone]

If you start with .130 mol/L of KI then after complete dissociation you would have .130 mol/L of K⁺ and .130 mol/L of I^-. Now if they had given you .130 *grams*/L of KI then you might have to do an approach like you wrote (the easiness of the mol concept is why Chemists use it  .

yeah, i didnt think about the foolishness of it until after i posted it, i was thinking id need to convert based on the percentage of the compound and then i relaized the potasium iodide would dissociate into equal parts.....thanks for the quick reply though, lol, hopefully i think simple stuff out a bit more in the future

[renge ishyo]

I remember getting confused with these things when I started out with Chem, that's just the way it goes 

[daistheputridone]

I remember getting confused with these things when I started out with Chem, that's just the way it goes 

you just grow accustomed to it i suppose

[daistheputridone]

i was going to post a seperate topic but this new question is interelated with the old one

i have to calculate the concentration of I-,(S2O3)2-, and (S2O8)2- in a solution of 15 ml KI, 5 ml Na2S2O3, 1 ml starch solution, 1 drop EDTA, 15 ml of amonium thiosulfate

now i have no clue where to begin...the KI and (S2O8)2-, are given to be .130 molar, but i cant seem to follow all of this to the concentration of I- or either of the other two