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?


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

  • $\begingroup$ 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 '14 at 2:47
  • $\begingroup$ So was my answer. $\endgroup$ – LDC3 Sep 7 '14 at 2:48
  • $\begingroup$ so there is no change - but the solution remains basic? $\endgroup$ – confused Sep 7 '14 at 2:50
  • $\begingroup$ Yes, the solution remains basic. $\endgroup$ – LDC3 Sep 7 '14 at 2:55

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