no i'm not correct!
u said that 1 M KMnO4 is equal to 5N, i said it it equal to N/5, that is, i said that 1N = 5M. i must have remembered it wrong.. and the correct formula must be N = M/x.
in case of thiosulfate, S2O3 2- is transformed into S4O6 2- , thus we need two electrons, and then we get M = 2N . is this correct?
now let's go back to the titration. usually when we want to calculate the normality of a solution indirectly, we dont just mixe the solution and then titrate only once!
i mean that, from the titration, i get the V of thiosulfate needed to titrate I2. the normality of thiosulfate is unknown. so at equivalence, the reactants react according to the stochiometric ratios, and nI2 = n thiosulfate/2 thus 2 N.V (iodine) = N.V (thiosulfate).
so "given" the number of moles of iodine, i calculate the normality of thiosulfate and then according to their relation written in the manual (and which i think is wrong) NV (permanganate) = NV (thiosulfate) we calculate the normality of permanganate.
and so we come back to the same problem, how to calculate the number of moles of iodine!
because when usually "I" do such an experiment, we dont just mixe at the first, we do a titration too, and fromt he titration we get the number of moles of iodine and then do a second the titration with thiosulfate and calculate its normality.
2kMnO4 + 10 KI + 8 H2SO4 ---> 5I2 + ...
here we have the volume of KI added. and they said it's 5-10 % (i dont know what that is), and the volume of the acid with its normality and the volume of KMnO4. but the acid, isnt just added to make an acidic medium? how can i know the limiting reagant to calculate the number of moles of iodine produced!!
i'm so sorry about the long post.. but there's one more thing, about the relation the wrote:
NV (permanganate) = NV (thiosulfate)
i would have said that, nI2 from the above equation is equal to 5/2 nKMnO4. and nI2 using the titration equation is n thiosulfate/2, so we have:
n / 2 thiosulfate = 5/2 n permang.
so n permanganate = n thio /5
so, using the normalities, we get:
5 N. V (permang.) = 2 N.V (thio)
and not NV (permang.) = NV (thio) as they said, isnt correct?
thank you very much.