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Primary Cells - pH changes during discharge

Alkaline Cell:

Manganese Dioxide Zinc Alkaline Cell

Anode (-) $\ce {Zn(s) + 2OH^{−}(aq) → ZnO(s) + H2O(l) + 2e^{−}}$

Cathode (+) $\ce {2MnO2(s) + H2O(l) + 2e^{−} → Mn2O3(s) + 2OH^{−}(aq)}$

Overall $\ce {Zn(s) + 2MnO2(s) → ZnO(s) + Mn2O3(s)}$

  • $\ce {OH-}$ ions are consumed at the anode
  • $\ce {OH-}$ ions are formed at the cathode
  • $\ce {same[OH^{−}]}$
  • pH - no change

Is this correct? Do pH changes occur during the discharge process?

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1 Answer 1

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No, the reaction does not produce hydroxide ions. But the solution is already basic (probably between pH 12 and 14).

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  • $\begingroup$ I fixed your edits - because I wrote it wrong at first... or have I corrected it incorrectly? Can you take a look again? $\endgroup$
    – confused
    Sep 7, 2014 at 2:47
  • $\begingroup$ So was my answer. $\endgroup$
    – LDC3
    Sep 7, 2014 at 2:48
  • $\begingroup$ so there is no change - but the solution remains basic? $\endgroup$
    – confused
    Sep 7, 2014 at 2:50
  • $\begingroup$ Yes, the solution remains basic. $\endgroup$
    – LDC3
    Sep 7, 2014 at 2:55

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