(a) Current of 1.5 ampere was passed through an electrolyte containing `AgNO_(3)` solution with inert electrodes. The weight of silver deposited was 1.5 g. How long did the current flow ?
(b) Write the reactions taking place at anode and at cathode in the above cell.
(c ) Give the reactions taking place at the two electrodes if they are made up of silver.

Explanation

(a) `Ag^(+)(aq)+e^(-)rarrAg(s)`
Molar mass of Ag =108 amu =108 g`mol^(-)`
108 g of silver was deposited by passing charge =96500 C
1.5 g of silver was deposited by passing charge` =((96500 C))/((108 g))xx(1.5 g)=1340.3 C`
Now, quantity of charge (Q) `="Current in amprers" xx"Time inseconds"`
`:.` Time for which current was pased `=("Quantity of charge")/("Current in amperes")=(1340.3 (As))/((1.5 A))=893.5 s`
(b) Reactions at different electrodes which are of inert nature
lonisation of silver nitrate (`AgNO_(3)`) and water proceed as follows :
`AgNO_(3)(s)overset((aq))rarrAg^(+)(aq)+NO_(3)^(-)(aq)`
`H_(2)Ooverset((aq))harr H^(+)(aq)+OH^(-)(aq)`
At cathode : `Ag^(+)` ions with less discharge potential are reduced in preference to `H^(+)` ions which will remain in solution. As a result, silver will bedeposited at cathode.
`Ag^(+)(aq)+e^(-)rarrAg(s)`
At anode : `OH^(-)` ions with less discharge potential are oxidised in perference of `NO_(3)^(-)` ions which will remain in solution.
`OH^(-)(aq)rarr OH+e^(-), 4OH rarr2H_(2)O(l)+O_(2)(g)`
Thus, silver will be deposited at cathode while `O_(2)` at anode.
(c ) Reactions taking place at silver electrodes
By using silver electrodes (attackble electrodes) following reactions will take place.
At cathode : `Ag^(+)` ions will be reduced to silver, which will be deposited.
`Ag^(+)(aq)+e^(-)rarr Ag ("deposited")`
At anode : An equivalent amount of of silver will be oxidised to `Ag^(+)` ions by releasing electrons.
`Ag(s)overset((aq))rarrAg^(+)(aq)+e^(-)`
The concentration of silver nitrate in solution will remain unchanged.