BATTERY:

 

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A  battery consist of two or more galvanic cells connected in series.There are two kinds of batteries-

1-PRIMARY BATTERY

2.SECONDARY BATTERY 

1-PRIMARY BATTERY: In primary battery when the reactant have been converted into product's no more electricity is produced.The cell reaction can not be reversed and the battery become dead.

2.SECONDARY BATTERY: In secondary battery a cell reaction can be reversed by passing the electricity through the battery (charging). It means that battery can be used again and again through a large number discharging cycle.

-The cathode consist of a graphite rod surrounding by powder MnO2+C black . The space between the electrodes is filled with  a moist pest of ZnCL2 & NH4Cl.

-Ammonia produced during the reaction for complex with Zn to give [Zn(NH3)4]2+.

- The cell has the potential of the nearly 1.5V.

 MERCURY CELL OR BUTTON CELL: The Anode consist of Zn - Amalgam and the paste of HgO and carbon act as Cathode .The Electrolyte is the pest of ZnO & KOH.

The cell  has a voltage of 1.53V and remains almost constant during its life.

SECONDARY BATTERY: (Lead Storage Battery ) : The most common example of a secondary battery is the Lead Storage Battery . The cell reaction can be reversed by passing Electricity through the battery .The following reaction occures in a lead storage battery .