STANDARDIZATION OF 0.01 N IODINE TITRANTProfessor of Biology and Chemistry University of Cincinnati Clermont College, Batavia OH 45103 |
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rvsd 11 May 1993, 27 Mar '94, 29 Mar '95, 24 March 96, 2 May 02 |
STANDARDIZATION OF 0.01 N IODINE TITRANTProfessor of Biology and Chemistry University of Cincinnati Clermont College, Batavia OH 45103 |
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rvsd 11 May 1993, 27 Mar '94, 29 Mar '95, 24 March 96, 2 May 02 |
This
operation determines the conversion factor (CF) for the iodine titrant
which, when multiplied times the mL titrant used, will convert it to mg
vitamin C. (Remember that a conversion factor = desired units/given units.)
Here, 10.0 mg of vitamin C is divided by the mL of iodine required to react
with it. This yields a CF with the units
mg vitamin C/mL iodine. Note that this standardization procedure is
required only for the initial step of vitamin C determinations, but not
when performing a determination on an unknown sample. (See other protocols
for specifics of technique, and reagent preparation.)
| 1. Deliver 10 mL of Rxn Mix into each of three 250 mL flasks (a repipet simplifies the operation.) | |
| 2. Pipet 1.00 mL 1% Vit C (10.0 mg) into each of the flasks (use a displacement pipetter). | |
| 3. Read and record the starting volume in the buret to the nearest 0.01 mL | |
| 4. Titrate the first flask with 0.01 N Iodine solution until the solution just turns faint blue. | |
| 5. Read and record the finishing volume in the buret, also to the nearest 0.01 mL. | |
| 6. Repeat the titration for the other two flasks. | |
| 7. Determine the volume of iodine solution used in each titration, determine the mean volume required for the three flasks. | |
| 8. Calculate the conversion factor for the iodine by dividing 10 mg Vit C by the mean mL iodine used, giving the conversion factor: |
