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You perform the titration as follows:

    • You dissolve 0.1446 g KIO3 in 25 mL H2O, and then added 2.05 g KI and 5 mL H2SO4. (solution I).
    • You dissolve 2.5153 g of the synthesized NaS2O3 in 100 mL H2 (solution II).
    • You titrate the solution II into solution I. 38 mL of solution II is requrid to reach the endpoint.

Calculate the % by weight of Na2S2O3 in the synthesized product and obtain the number of waters in the crystal form.

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Miguel Matienzo
Miguel MatienzoLv10
25 Mar 2021
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Related questions

Weigh about 1.2 g of Na2S2O3.5H2O and 0.04 g of Na2CO3 and transfer the solids into a 100 mL volumetric flask. Add a small amount of deionized water to dissolve the solids and fill with deionized water until the mark swirling constantly until a homogenized mixture results.

Part 2: Weigh about 0.2 g of KIO3 then transfer the solution into a 100 mL volumetric flask. Fill the flask with deionized water until the mark swirling constantly until a homogenized mixture results.

Part 3: Clean a burette with deionized water; rinse it with a small (about 5 mL) of the sodium thiosulfate solution then fill the burette with the sodium thiosulfate solution to eye level. Record the initial reading of the burette before attempting the titration.

Measure 20 mL of the potassium iodate solution into an Erlenmeyer flask, add 0.5 g of KI crystals and 2.5 mL of 1 M H2SO4, and swirl until all the KI dissolves. Titrate immediately with the sodium thiosulfate solution until a light yellow solution results. Add 1 mL of the starch solution and keep titrating until the color disappears.

I2 + 2Na2S2O3 → 2NaI + Na2S4O6

IO3- + 5I- + 6H+→ 3I2 + 3H2O

Na2S2O3 Titration Volume: 13.96 ml

Calculate the concentration of the Na2S2O3 using your titration data.

Calculate the weight percent of ascorbic acid in a tablet of Vitamin C from the following data: A 100 mg sample of a crushed Vitamin C tablet was dissolved in 40 mL of H2SO4 and 20 mL of water. Two grams of KI and 30. mL of 0.0126 M KIO3 solution was added, and the mixture titrated to a starch endpoint. The titration required 26 mL of 0.0490 M thiosulfate solution.

Direction:

Part I - Prepare and standardize a solution of Sodium Thiosulfate 1. Prepare 250 mL of a solution which is approximately 0.025 M Na2S2O3• 5H20. Because sodium thiosulfate is a hydrate, it cannot be used as a primary standard. It must be standardized in order to determine its exact concentration. (Note for Su’17: this solution has already been prepared for you). 2. Pipet 10.0 mL of 0.01 M KIO3 into a 150 mL Erlenmeyer flask. Add about 20 mL of distilled water to the flask. 3. Dissolve about 2 g of solid KI to the KIO3. The solution should turn a dark orange-brown. Add about 20 drops of 2M HCl and swirl to mix completely. 4. Calculate the approximate amount of Na2S2O3 that will be required to reach the endpoint, assuming that the Molarity of the Na2S2O3 will be approximately 0.025 M. 5. Quickly add all but about 2 or 3 mL of the volume you calculated above to the flask. 6. Add about 40 drops of a 2% starch solution. The solution should turn dark blue. 7. Continue adding Na2S2O3 dropwise until the blue color just disappears. Record the volume of Na2S2O3 in your lab notebook. 8. Repeat one more time. Calculate the concentration of the Na2S2O3 from each trial and average your results. If they differ greatly, a third trial may be necessary. Part II - Prepare a saturated solution of Ca(IO3)2 1. Combine 100.0 mL of 0.20 M KIO3 with 40 mL of 1M Ca(NO3)2 in a 150-mL beaker. Stir to mix the solutions completely. A white precipitate of Ca(IO3)2 should form. 2. Let the mixture stand a few minutes, then filter into a dry flask, through a dry filter paper using gravity filtration. Cover the solution with parafilm.

Show me part2 how to calculate the concentration of iodate ion in the filtrate. Using the equation editor, insert---> eqatuion.

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