How many moles of bromate ions (BrO32-) are consumed for every one mole of thiosulfate ions present? Hint: What species do the reactions of bromate and thiosulfate have in common with each other?

Question

Consider:

6 I^- + BrO₃^- + 6 H⁺ -> 3 I₂ + Br^- + 3 H₂O



I₂ + 2 S₂O₃^2- -> 2 I^- + S₄O₆^2-

1.How many moles of bromate ions (BrO32-) are consumed for every one mole of thiosulfate ions present? Hint: What species do the reactions of bromate and thiosulfate have in common with each other? Make your units cancel out!

2.Based on your answer to question 1, what is the concentration of bromate consumed by thiosulfate in each reaction?

  

3.Write an expression describing rate as a function of the disappearance of bromate and change in time.

Answer 1

So Iris E., That was your assignment. But --

What is your question? And where are you, mentally, as you look at this problem?

If I don't see any evidence of work on it, I can't really figure out what you need in terms of conceptual approach (or calculation, or ....)!

As oxidizing agents, BrO3(2-) is stronger than I2 which is stronger than S4O6(2-). So the oxidation "knocks its way down" through that series. The I2 is the "fall guy" which shuttles back and forth to accomodate both reactions.

Incidentally, you may recognize BrO3(2-) as the bleaching agent for commercial "bleached" = bromated bread flour. Not surprising that some nutritional quality is lost in that process!

-- Cheers, -- Mr. d.