Question

Is the calculated concentration for IO₃^- in the data table correct, and if not, how do I calculate it. Also, the questions below the data table in the second picture. How are they calculated?

2. The molar solubility of Cal(IO3)2 in pure water Temperature of the saturated solution of calcium iodate: Volume (or mass) of saturated calcium iodate solution titrated:O -24 °C ted:1 Q mL (or g) Data Trial 1 Trial 2 Trial 3 Volume of Na2S203 titrant Final buret reading Initial buret reading Net volume of Na2S20, Calculated concentration of 10, 245mL mL mL mL - mL mL 23.S m 6.30 mL For each trial, calculate the concentration of 103-; show a sample calculation in the space below. Average IO3-concentration. CallO3)2 Macroscale: Fill a 25- or 50-mL buret with 0.050 M sodium thiosulfate solution, taking care to 8 rinse the buret and to expel all bubbles from the tip of the buret. Obtain about 30 mL of saturated calcium iodate solution in a clean, dry flask. (The sample must not show any visible solid particles of undis- solved calcium iodate.) Put 50 mL of deionized water - e and 2 g of KI into a 250-mL Erlenmeyer flask and swirl to dissolve the KI. Then, using a pipet-filling device to e fill the pipet, transfer 10 mL of the saturated calcium iodate solution into the 250-mL flask and add 10 mL of 1.0 M HCl. (10-mL graduated cylinders may be 3 used to measure the saturated calcium iodate and 1.0 M HCl solutions.) When the HCl is added, the solu- tion should turn brown. Without delay, titrate the solution with 0.05 M sodium thiosulfate until the solution is yellow. Then add 5 mL of 0.1% starch indi- cator. The solution should turn blue-black, the color of the starch-iodine complex. Continue the titration until you get a sharp change from blue to a colorless solution. Record the final buret reading. Repeat the titration procedure with a second sample. The volumes should agree to within 5%. (A possible source of error is the air oxidation of I to give 12. If the solution is allowed to stand for too long before it is titrated, the oxidation will produce values that are too high.)

Answer 1

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