Analyt chem -Lab Report 5 - Ly Ngo CHM 3120C Section 001...

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Ly Ngo October 26, 2010 CHM 3120C Section 001 Post Lab 6: Iodometry, Volumetric Determination of Sodium Thiosulfate (Na2S2O3) Introduction The purpose of this experiment is calculate the concentration of sodium thiosulfate solution. This is done by using sodium thiosulfate solution to titrate a known concentration of potassium iodate solution. With the correct methods of titration, and knowing the number of moles potassium iodate contains as well as how much volume of sodium thiosulfate is used, determination the concentration of sodium thiosulfate solution is accessible. Thus, by performing titration accurately and precisely, the calculated concentration of the unknown or the thiosulfate solution is closely identical to the concentration used. Materials & Methods The students is going to begin the lab by obtaining 2 grams of dried KIO3, 2 gram of iodate-free KI, 6M HCl, distilled water, starch indicator, and 200 mL sodium thiosulfate solution. Next, potassium iodate solution is going to be prepared by using a powder funnel to transfer 1.2 g of dried KIO3 into a 500 mL volumetric flask. Distilled water is then diluted to the mark using an eye-dropper. Then, 50 mL is transferred to a 250 mL Erlenmeyer flask along with 2 grams of iodate-free KI, 2 mL of 6M HCl. The solution is going to be titrated until pale yellow appears.

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