While giving labelled diagram of dry cell write reactions taking place

1.	While giving labelled diagram of dry cell write reactions taking place at cathode and anode.
Answer» Solution :PRIMARY cells arethosein whichthe electrodereactionscannotbereversed by anexternalelectricenergysource. Inthesecells, thereactionoccursonlyarenotchargeable . (a)Drycell . Thedry cell wasinvented by G.leclanche.It CONSISTS of zinccylinder. thisis filledwitha paste of `NH_4 Cl`and littleof `ZnCl_2` in theformofpastein water. thezinccylinderactsas anodethecathodeiscarbonrod . thecarbonrodis SURROUNDEDBY a blackpasteof magneticdioxide`(MnO_2)` andcarbonpowder whenthe cellis openatingzincloseselectrons and`Zn^(2+)`ionsdissolvein theelectrolyte . theelectron passaroundthe external circuitand are takenup atcathodethis causesdischargecircuit and aretakenupat cathodethis causesdischargeof `NH_(4)^(+)` ionsfromthe ELECTRONLYTE the reactionoccrringat theelectronsare givenbelow Atanode ` Zntozn^(2+)+ 2E^(-)` atcathode `2NH_4^(+)(AQ)+ 2MnO_2(s)+2e^(-)to Mn_2 O_3(s)+NH_3 +H_2 O` it givesa voltageof about1.5 V (b )uses. thedrycellsareused intorches , toysflash lighterscalculators, tape - recorders and inmanyotherdevices .

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