dry cell (1 Viewer)

[zinc]

is the cathode the graphite core or the graphite, the manganese dioxide and the ammonium chloride or is the ammonium chloride the electrolyte? Very confused.
Thanks

 

[SkimDawg]

anode: Zn ----> Zn(2+) +2e
cathode: NH4(+) + MnO2 + H2O + e ---> Mn(OH)3 + NH3
the carbon graphite rod is the cathode. the zinc casing is the anode. the C, MnO2 and NH4Cl im pretty sure is the electrolyte (the paste is like a mixture of the 3)

 

[danz90]

anode: Zn ----> Zn(2+) +2e
cathode: NH4(+) + MnO2 + H2O + e ---> Mn(OH)3 + NH3
the carbon graphite rod is the cathode. the zinc casing is the anode. the C, MnO2 and NH4Cl im pretty sure is the electrolyte (the paste is like a mixture of the 3)

the electrolyte past is made up of NH₄Cl / ZnCl₂ . MnO₂ is the oxidant, and skimdawg rightly said that C(s) is the cathode.

Those equations for oxidation and reduction are also correct

 

[zinc]

ok thanks!

 

[totallybord]

for the reduction half eqn, i got another eqn from another textbook
2MnO +2NH4+ + 2e ->Mn2O3 +H2O + 2NH3
?
is that still ok?

 

[danz90]

for the reduction half eqn, i got another eqn from another textbook
2MnO +2NH4+ + 2e ->Mn2O3 +H2O + 2NH3
?
is that still ok?

from knowledge, the oxidant is MnO₂, not MnO.
So then, you use:

Oxidation: MnO₂(s) + NH₄⁺(aq) + H₂O(l) + e^- ---> Mn(OH)₃(s) + NH₃(aq)

 

[totallybord]

yeah sorry its 2MnO2 and the rest of the eqn
is that wrong still ?

 

[danz90]

yeah sorry its 2MnO2 and the rest of the eqn
is that wrong still ?

hmm, there shouldn't be a 2 in front of all the species.
its a 1:1:1:1 stoichiometric ratio.

 

[Azreil]

Maybe it was put like that to balance out the e on both sides and hence determine the final equation?

 

[danz90]

Maybe it was put like that to balance out the e on both sides and hence determine the final equation?

yeah, good point.