[ivanka]

i have no idea how to calculate all the calculations
we did the experiment last week
we need to prepare and calc the concentration of a solution of potassium iodate by using primary standard KIO3 (s).
then prepare a solution of sodium thiosulfate and standardize it by titration with potassium iodate
and finally use the iodate and thiosulfate solutions to analyze a vitamin C tablet to determine how many mg of ascorbic acid it contains.
i got all the datas but i don't know how to use it.

first i dried 2.6462g KIO3
then for the titration of KIO3 with sodium thiosulfate
Trial 1 ~ 2.0156g KI(s) added
           end-point - 43.78ml

Trial 2 ~ 2.0172 KI added
            end-pt - 43.79

Trial 3 ~ 2.0182 added
              end-pt - 43.68


then the other sets of datas ( analysis the vitamin C pill)

Trial 1 ~
vitmin C pill - 0.9410g
after grinded -  0.9351g
KI (s) added - -2.0086g
end-pt - 26.78ml



Trial 2~
vitamin C pill - 0.9466g
after grinded - 0.9445g
KI (s) added - 2.0081g
end-pt - 26.51 ml



Trial 3~
vitamin C pill - 0.9420g
after grind - 0.9334g
KI (s) added - 2.0083g
end-pt - 26.48



it says we will need to dividing powder weight by pill weight, so we will have an accurte measure of the fraction of the pill that we actually titrate.

so...can anyone help me with all these calculation...i have no idea
please help me ~

[Borek]

Start with reaction equations, every titration is just a simple stoichiometry.

http://www.titrations.info/titration-calculation

http://www.titrations.info/iodometric-titration-Vitamin-C