(a) What type of a battery is the lead storage battery ? Write the anode and the cathode reactions and the overall occuring in a lead storage battery when current is drawn from it.
(b) In the buttom cell, widely used in watches the following reaction take place
`Zn_((s)) + Ag_(2)O_((l)) rarr Zn^(2+)(aq) + 2Ag_((s)) + 2OH_((aq))^(-)`.
Determine `E^(@)` and `DeltaG^(@)` for the reaction.
(given : `E_(Ag^(+)//Ag)^(@) = +0.80 V , E_(Zn^(2+)//Zn)^(@) = - 0.76 V)`

Explanation

(a) It is a secondary cell.
`{:("Anode":" "Pb+SO_(4)^(2-)rarrPbSO_(4)2e^(-)),("Cathode":" "PbO_(2)+PBO_(2)+4H^(+)+2SO_(4)^(2-)rarrPbSO_(4)+2H_(2)O):}`
Overall reaction : `Pb+PBO_(2)+4H^(+)+2SO_(4)^(2-)rarrPbSO_(4)+2H_(2)O`
(b) Zn is oxidised and `Ag_(2)O` is reduced.
`E_("cell")^(0)=E_(Ag_(2)O),Ag_("reduction")-E_(Zn//Zn_(("oxidation"))^(2+)`
`= 0.8 - (-0.76) = 1.564 V`
`DeltaG^(@)= - nFF_("cell")^(0) = 2 xx 96500 xx 1.56 = 301080 J//"Mol"`