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Unformatted text preview: swirl until the solids have dissolved. Continue gradually
adding water and swirling the flask to keep the contents well mixed, and finally add
water from a disposable pipet to bring the liquid level to the mark. Do a final mixing
by inverting and swirling the flask at least 30 times. Divide the solution
approximately in half into two 250 mL beakers. To one beaker add 1 g of oxalic acid
and stir with a glass rod until the oxalic acid has dissolved. Label each of the beakers
so that the one containing oxalic acid can be distinguished from the one without. Add
1 mL of 0.05 M ferric nitrate solution to each of the beakers and set them aside. 77 Part II. Titrations
Do these titrations one at a time--in other words, do not let ascorbic acid solutions sit
around exposed to the atmosphere for very long.
Assaying your NBS solution: With a volumetric pipet take a 10 mL aliquot of the
"partnership's" standard ascorbic acid solution and add it to a 125 mL Erlenmeyer
flask that already contains 20 mL of water, 2/3 mL of 6 M acetic acid, 5 mL of 4% KI
solution and 1 mL of starc...
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- Spring '07