In an iodometric titration, excess potassium iodide solution (KI) is added to the sample.Analyte such as chlorine liberates iodine from KI under acidic condition. Liberated iodine is titrated against standard sodium thiosulphate.
The concentration of analyte in the sample is given as
= (mL sodium thiosulphate x normality of sodium thiosulphate x milliequivalent weight of analyte) / mL of sample
Why do we need to multiply by normality of sodium thiosulphate?
mL Na2S2O3 x N Na2S2O3 = # milliequivalents.
Then #milliequivalents x milliequivalent weight = grams.posted by DrBob222