Analysis of commercial vitamin C tablets

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Analysis of commercial vitamin C tablets

Date: 11-10-2010

Objective

To determine the vitamin C content in commercial vitamin C tablets by titration between vitamin C (ascorbic acid) & iodine solution. Hence, compare this data with the manufacturer's specification.

Procedures

1. 0.6808g potassium iodate(V) , KIO3,was accurately weighed.

2. KIO3 (s) was then dissolved in de-ionized water in a beaker.

3. The solution was made up to 250cm3 in a volumetric flask.

4. Sodium thiosulphate, Na2S2O3, was standardized by part of the standard KIO3 solution in the following steps:

(a) 25cm3 of the standard KIO3 solution was pipetted into a conical flask

(b) 5cm3 of 1M potassium iodide, KI, together with 10 cm3 of 0.5M sulphuric acid, H2SO4, were also added into the conical flask.

(c) The mixture was immediately titrated with approximately 0.1M Na2S2O3 solution.

(d) These steps were repeated for 2 times to obtain a more accurate titration data.

(e)When the reaction mixture became pale yellow, 5 drops of freshly prepared starch solution were added.

(f) The titration was continued until the end-point was reached.

(g) The molarity of Na2S2O3