Chemistry Forum

In a vitamin C analysis, triiodide ions are generated in solution by the following unbalanced reaction in acidic solution:

IO₃- (aq) + I- (aq) --> I₃- (aq)

I₂- is determined by titration with Na₂S₂O₃ solution. The products are (I-) and (S₄O₆₂-).

a) Balance the equation for the half reaction of IO₃- (aq) with I- ions.

b) A sample of 0.6013 g of KIO₃ was dissolved in water; HCL and sodium potassium iodide were then addeed in excess. What is the minimum weight of solid KI and the minimum volume of 3.00 M HCL required to convert all of the IO₃- ions to I₃- ions?

c) Write and balance the stoichiometric equation for the reaction of S₂O₃₂- with I₃- in acidic solution.

1) to balance half reactions you need to consider acidity of the solutions.
Unbalanced:
IO₃^-(aq) + I^-(aq) + H⁺ = I₃^-(aq) + H₂O

Balanced:
http://www.webqc.org/balance.php?reacti ... q%29%2BH₂O

2)
Unbalanced:
2 S₂O₃^2- + I₃^- = S₄O₆^2- + 3 I^-

Balanced:
http://www.webqc.org/balance.php?reacti ... 2BI%7B-%7D

Can you solve this problem now? Let me know if not.

J. Mac