Question

Three electrolytic cell `A,B`, and `C` contaning solutions of `ZnSO_(4), AgNO_(3)`, and `CuSO_(4)`, respectively, are connected in series. A steady current of `1.5A` was passed through them until `1.45 g` of silver deposited at the cathode of cell `B`. How long did the current flow ? What mass of copper and zinc were deposited ?

Answer 1

`Ag^(+)+e rarr Ag :. E_(Ag) = (108)/(1)`
Eq. of `Zn =` Eq. of `Cu =` Eq. of `Ag = (i.t)/(96500)`
or `(1.45)/(108//1) = (1.5 xx t)/(96500)`
`t = 864sec = 14.4 min`
Now, Eq. of `Zn = (w)/(E) = (1.5 xx 864)/(96500) = 0.0134`
`(Zn^(2+)+2e rarr Zn :. E_(Zn) = (65)/(2))`
`w_(Zn) = (65 xx 0.0134)/(2) = 0.437 g`
Also Eq. of `Cu = 0.0134`
`(Cu^(2+)+2e rarr Cu :. E_(Cu) = (63.6)/(2))`
`:. w_(Cu) = (0.0134 xx 63.6)/(2) = 0.427 g`