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I was studying NCERT book of chemistry about chemical properties of hydrogen peroxide. First there is a chemical equation under a subtopic named 'Oxidising action in acidic medium' which is...

$$\ce{2Fe^{2+} + 2H^+ + H_2O_2 \rightarrow 2Fe^{3+} + 2H_2O}$$

Note here that there are hydrogen ions in the reactant side because it is in acidic medium.

Then another subtopic named 'Oxidising action in basic medium' has reaction

$$\ce{2Fe^{2+} + H_2O_2 \rightarrow 2Fe^{3+} + 2OH^-}$$

Now in this equation there is no hydroxide ions as it should be because it is basic medium.

I am not asking about its oxidizing and reducing properties or how it works. I know that oxygen atom of $\ce{H_2O_2}$ has $-1$ oxidation state. I am just asking why isn't there any hydroxide ion in the reactants.

Sorry if it is foolish doubt. Thanks in advance.

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  • $\begingroup$ Because you don't need OH- to form Fe3+. $\endgroup$ – orthocresol Nov 17 '15 at 11:39
  • $\begingroup$ @orthocresol why not? $\endgroup$ – manshu Nov 17 '15 at 11:42
  • $\begingroup$ maybe it has to do something with reaction rates. maybe if there is no hydroxide ion already present, the reaction will proceed very fast and can go through alternative path way to give something else as product. so maybe its a kinetic control here $\endgroup$ – Punarbasu Roy Nov 17 '15 at 12:26
  • $\begingroup$ @PunarbasuRoy then why this reaction should occur in basic medium as stated in the book? $\endgroup$ – manshu Nov 17 '15 at 12:28
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    $\begingroup$ Nothing to do with rxn rates - just stoichiometry - look at the balanced equation you have, you can add OH- on the left if you want, all that happens is that another OH- is added on the right, if it's not involved in the reaction why bother adding it to the equation? it's like mixing aqueous AgNO3 and NaCl, you can write $\ce{Ag+ + Cl- -> AgCl}$, just because water is in the reaction system doesn't mean it has to be in the equation - would you write $\ce{Ag+ + Cl- + H2O -> AgCl + H2O}$? $\endgroup$ – orthocresol Nov 17 '15 at 17:06

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