Zn is a metal which forms cations 

But why Zn container acts as an anode in a dry cell

Asked by lovemaan5500 | 7th Jan, 2018, 03:51: PM

Expert Answer:

In the dry cell, the Zn container acts as an anode and graphite is act as a cathode surrounded by MnO2 + Carbon.
here is a paste of NH4Cl and ZnCl2 is filled in between the electrodes.
Cell reaction: 
At anode:
Zn(s) → Zn2+ + 2e- 
At cathode:
2MnO2(s)  + NH4+(aq) + 2e- →Mn2O3(s) + 2NH3(g) + H2O
 
Zn2+ combines with NH3 to form diammonium Zn(II) cation.
The dry cell has a short life, as NH4Cl corrodes Zn container even when the cell is not in use.

Answered by Ramandeep | 7th Jan, 2018, 09:20: PM

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