Dry cell ???

[person]

Hey im having trouble understanding all the mechanisms of the following !!

 

" A dry cell is contained in a zinc housing that acts as the anode. the other electrode, the cathode, is a graphite rod in the middle of the cell. a layer of manganese oxide and carbon black surounds the graphite rod, and a thick paste of ammonium chloride and zinc chloride serves as the electrolyte.

 

The cell reactions are:

 

Zn(s)-> Zn^2+ + 2 e^-

 

2MnO2(s) + 2NH4^+ + 2 e^- -> Mn2O3(S) + 2NH3(aq)+ H2O

 

Pls explain:

1. the role of all the chemicals (those directly involved and what the carbon black does).

2. .... Cant remember

 

Thanx !!!!