|Wet and Dry Cell Batteries|
|Primary Cells - A cell that will discharge an electric
from a chemical reaction but not one that is capable of being reversed
|Secondary Cells - Cells that are capable of being reversed
original condition so that the Eo potential is restored.
|Storage Batteries - Car, Truck, Motorcycle etc.|
|The 12 V battery consists of 6 Voltaic cells connected in series
so that their voltages are additive.
The anode and cathode are immersed in an electrolytic solution containg sulphuric acid. The anode is spongy lead and the cathode is lead dioxide.
|The anode reaction is:
<===> PbSO4 + H+1 + 2e-1
|The cathode reaction is:
HSO4-1 + 3H+1 + 2e-1
<====> PbSO4(s) + 2 H2O
|The total reaction is:
| Pb(s) + PbO2
+ 2 H+1 + 2 HSO4-1
2 PbSO4 + 2 H2O
|As the battery discharges the density of the sulphuric
decreases. In older times the concentration of this could be
at a garage. The older batteries also had a gas fitting at the
of each cell that allowed any H2 gas created to
this is course is an open system and the H2 that escaped is
unavailable to recombine in the reverse reaction.
|Todays' batteries are sealed. The H2 gas is
an equilibrium set of conditions is in place. this means that the
battery should last longer, be able to supply more consistent current
be recyclable once finished it life expectancy.
|The reactions that are believed to occur in a dry cell are
|Cathode: 2 MnO2 + 2 NH4+1
+ 2e-1 ----> Mn2O3
+ 2 NH3 + H2O
|Anode: Zn + 4 NH3 -----> Zn(NH3)42+ + 2 e-1|