Redox equations

1. Aug 22, 2007

big man

1. The problem statement, all variables and given/known data
Write the half equation for the cathodic reaction of oxygen

3. The attempt at a solution
Now I know that the cathodic reaction will be reduction and so the oxygen will be gaining electrons. I thought I had the answer from the lecture notes, but then I thought of another possible equation that would work too and I don't know which one is right??

The two equations are as follows:
equation from notes( the notes say that this is the most common)
$$O_2 + 2H_2O + 4e^- ->4OH^-$$

the equation I came up with
$$O_2 + 4H^+ + 4e^- ->2H_2O$$

Are these just two possible half equations for the cathodic reaction of oxygen or is one wrong??

Thanks for your time

2. Aug 24, 2007

Gokul43201

Staff Emeritus
I think we need more context here. Both reactions are legal, and likely occur at quite different potentials, so additional details are necessary.

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook