Molar concentration of stock KIO3 solution: 0.0187M ± 1x10-5 M
2. Molar concentration of dilute KIO3 solution: 0.00187M ± 2x10-5
3. Molar concentration of Na2S2O3 solution: 0.01087M ± 5x10-5
Average Volume used: 15.62 mL ± 0.04 mL
Discussion:
The lab took four trials because when the titration was finished, the second, third, and fourth volumes agreed to ± 0.2 mL. Some observations that were made was that after adding 0.2 grams of KI, 1mL of 1M sulfuric acid, and 10.00 mL of vitamin C that the solution resulted in a dark orange color.2 Continuing titration, the solution turned into a pale yellow color. Addition of 5 drops of starch solution, reactions occurred changing the color of the solution from pale yellow to a blue. Some trials would change colors quicker compared to other trials. It could have been human error when it comes to the variations in the results. The overall average volume used during titration was 15.62 ml ± 0.04 mL. The mass of Vitamin C was calculated by first finding the number of moles that I2 that reacts with Na2S2O3. Knowing the ratio of moles of I2 to Vitamin C is 1:1 resulted in the moles of vitamin C easily determined.2 Knowing what the moles of vitamin C was, the mass of vitamin C had to be found. The product of the mass received was 493 mg ± 26 mg. The mass of the tablet given by Equate is 500 mg.2 The results seem like fairly accurate but according to the numbers it does not match. In my calculations, the number of moles of Na2S2O3 added in the titration was 1.7x10-4 M ± 1.2 M was not accurate. This resulted in a large number of 493 mg ± 26 mg. This inaccurate concentrated standard solution of KIO3 from Lab F resulted in an inaccurate mass of Vitamin C to be 493 mg ± 26 mg. All measurements included in the lab used uncertainty and those uncertainties were included in the measure resulting in a much more accurate values. A more accurate concentrated solution of KIO3 from Lab F would result in