Analysis of Commercial Vitamin C Tablets

1970 Words Nov 5th, 2008 8 Pages
Analysis of commercial vitamin C tablets
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.
Principle
In this analysis, certain amount of iodine solution, which is known in excess, is added to acidified ascorbic acid solution. Brown iodine can be easily reduced by acidified ascorbic acid to form colourless iodide ion: ← Equation I The excess iodine is then back titrated by standard sodium thiosulphate solution, by using a burette and starch solution (used as end point indicator) Similarly, iodine can also be
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of moles of I2 added to react with vitamin C = 9.550761x10-4 mol No. of moles of S2O32- reacted by excess I2 = 0.064099M x 0.012175dm3 = 7.804061x10-4 mol From equation II, no. of moles of excess I2 = 7.804061x10-4 ÷ 2 mol = 3.902030 x 10-4 mol ∵ No. of moles of I2 is

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