Calculating ξ° value for a galvanic cell

[Phyzwizz]

Calculate the ξ° value for the galvanic cell:
IO₃(aq) + Fe²⁺(aq) <--> Fe³⁺(aq) + I₂(aq)

So I found the half reactions to be:

5Fe²⁺(aq) --> 5Fe³⁺(aq) + 5e^- Reducing agent 0.77V
6H⁺(aq) + 5Fe²⁺(aq) + 5e^- --> I₂(aq) + 3H₂O Oxidizing agent

The problem I have is that I can't find the standard reduction potential for the cation's half reaction. Do I just use the potential for I₂(s) + 2e^- --> 2I^- or this something special that I'm missing?

Thanks!

 

[Borek]

Calculate the ξ° value

ξ°? and not E₀?

IO₃(aq) + Fe²⁺(aq) <--> Fe³⁺(aq) + I₂(aq)

IO₃(aq)? and not IO₃^-?

It can be difficult to not reduced iodine further to I^- in the presence of Fe²⁺, but perhaps with right stoichiometry reaction will stop at I₂.

5Fe²⁺(aq) --> 5Fe³⁺(aq) + 5e^- Reducing agent 0.77V

Why 5?

6H⁺(aq) + 5Fe²⁺(aq) + 5e^- --> I₂(aq) + 3H₂O Oxidizing agent

This is completely off - please check if that's what you meant.

The problem I have is that I can't find the standard reduction potential for the cation's half reaction.

Not surprising - reaction you wrote doesn't make sense.