Hi everyone, I am a Nursing student taking my 3rd quarter of General Chemistry and I am having quite some trouble figuring out how to calculate the moles of iodine absorbed by this solution:
10 mL of dichloromethane, 20.0 mL of Hanus reagent, 10 mL of 15% KI solution and 20 mL of distilled water; Mixed and titrated with ~0.2 M sodium thiosulfate solution from a 50 mL buret.
Once titrated I added 2mL of 1% starch solution and titrated until the blue color was gone.
The way my instructions have me calculating this is: moles of I atoms absorbed = (B - S) x M
where: B = liters of Na2S2O3 for blank titration
S = liters of Na2S2O3 needed to titrate halogen unabsorbed by the sample
(B - S) = liters of Na2S2O3 equivalent to halogen absorbed by the sample
M = molarity of Na2S2O3, moles/liter
The mass of iodine absorbed by the sample is: grams of iodine adsorbed = moles of iodine atoms absorbed
x molar weight of iodine atom
(The molar weight of iodine atom is 126.9 grams/mole)
The Iodine Number is defined as the number of grams of iodine absorbed by 100 grams of fat: Iodine Number = grams of iodine absorbed by sample x 100
sample weight of fat in grams
I started out with 50mL of of titrate in my buret, and once the titration was complete I had 46.36mL left, which means 3.64mL is the volume of Na2S2O3 used to titrate blank, I'm guessing.
I know this may be clear as daylight for a few of you, but its exam week and I am TOTALLY burnt out over this. Someone help me please. If you can, I would be forever grateful.