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How come the oxygens transferred in redox reactions are always the $\ce{O^{2-}}$anion?

For example, I have this set of rules, and the rules are implicitly referring to the $\ce{O^{2-}}$ anion, a potent base (otherwise the rules wouldn't make sense; for example, it makes sense that a base in acidic solution is protonated to water, and that a strong base in basic solution is leveled to hydroxide ion).

In other words, how come, when electrons are transferred, such as in this unbalanced reaction:

$\ce{ClO_{3}^- + 6I^- \leftrightharpoons 3I_2 + Cl^-}$

The $\ce{O^{2-}}$ anion is formed (if only to be consumed again)? I remember my prof would say that specifically 3 $\ce{O^{2-}}$ anions "disappear".

Why not the $\ce{O^{-}}$ anion or simply $\ce{O}$? Does this have to do with stability?

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I think you are misunderstanding the meaning of superoxide and the rules.

Superoxide is $\ce{O_2^-}$

Superoxide is NOT $\ce{O^{2-}}$ as you have written.

The rules are referring to hydroxide which is $\ce{OH^-}$, not superoxide.

The reason hydroxide is used to balance equations in basic aqueous solution is:

$\ce{H_2O \leftrightharpoons H^+ + OH^-}$

There is hydroxide present in aqueous solution, but not superoxide, peroxide, hydroxyl radial, etc.

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  • $\begingroup$ What's the origin of this hydroxide ion? $\endgroup$ – Dissenter May 30 '14 at 18:40
  • $\begingroup$ water is in equillibrium with hydroxide and hydronium, according to the equillibrium constant $K_w$. The rules are for aqueous solutions. In high pH aqueous solution there is necessarily a high concentration of OH- $\endgroup$ – DavePhD May 30 '14 at 18:42
  • $\begingroup$ But in the case of the chlorate anion, the disappearing oxygen goes where? And the oxygen comes from water? $\endgroup$ – Dissenter May 30 '14 at 18:43
  • $\begingroup$ Well, in acidic conditions this can happen: ClO3− + I− + 2H+ → HOI + HClO2 en.wikipedia.org/wiki/Iodine_clock_reaction, but if you are following the rules, oxygen would go to water or hydroxide depending upon pH $\endgroup$ – DavePhD May 30 '14 at 18:47
  • $\begingroup$ water or hydroxide will form from protons or water and the oxygen of the reactant(s) $\endgroup$ – DavePhD May 30 '14 at 18:52

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