I have recently completed an experiment with hydrogen peroxide (5%), 0.1M KI and 1M NaOH.

Is the sodium hydroxide a reactant or a catalyst in this experiment?


In basic solution the half reactions are:


$\ce{H2O2 + 2 e- -> 2 OH-}$


$\ce{I- + 6 OH- -> IO3- + 3 H2O + 6 e-}$

So the overall reaction is

$\ce{3 H2O2 + I- -> IO3- + 3 H2O}$

thus $\ce{OH-}$ is overall neither a reactant nor a product. Hence it is either a catalyst, an inhibitor, or a spectator ion.

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