Fresh fruit juice contains high level of vitamin C. Jennifer investigated vitamin C content in a fresh orange juice sample using redox titration and starch indicator. Triiodide was generated to oxidize vitamin C in sample: 2I¯(aq) + I¯(aq) → I3¯(aq) + 2 e¯. Given a 50 mL orange juice sample required 10 min to oxidize vitamin C (176 g/mol) completely under constant current of 30 mA. Calculate the amount of vitamin C (in g/L) present in orange juice sample. (F = 96485 C/mol e¯)
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d) Fresh fruit juice contains high level of vitamin C. Jennifer investigated vitamin C content in a fresh orange juice sample using redox titration and starch indicator. Triiodide was generated to oxidize vitamin C in sample: 2I¯(aq) + I¯(aq) → I3¯(aq) + 2 e¯. Given a 50 mL orange juice sample required 10 min to oxidize vitamin C (176 g/mol) completely under constant current of 30 mA. Calculate the amount of vitamin C (in g/L) present in orange juice sample. (F = 96485 C/mol e¯)
e) H2S content can be determined quantitatively via coulometric titration. In this case, I3¯ was used as titrant while KI serves as mediator. Assume that 50 mL of unknown sample was
pipetted into a coulometric cell. Subsequently, excess KI was added and titration began. A small amount of starch powder was added after 5 minutes to visualise the titration end point.
Given a constant current of 94.6 mA was applied throughout the entire
H2S(aq) + I3¯(aq) + 2H2O(l) → 2H3O+(aq) + 3I¯(aq) + S(s)
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