Three elctrolytic cells A,B,C containing solutions of ZnSO4,AgNO3 and CuSO4 respectively are connected in series. A steady current of 1.5 ampere was passed through them until 1.45 g of silver deposited at the cathode3 of cell B. How long did the current flow ? What mass of copper and zinc were deposited ? [Atomic masses; Cu = 63,5, Zn = 65.3; Ag = 108]
(a) Ag+(aq)+e−1 mol→Ag(s)1mol(108 g)
108 g silver are deposited by electricity = 96500C
1.45 g silver are deposited by electricity
=(96500C)×(1.45g)(108 g)=1295.6C
Current(I) = 1.5 amperes
Time (t)=QI=(1295.6C)(1.5A)=863.7s=14 min 39s
(b) Cu2+(aq)+2e−2F(2×96500 C)→Cu(s)63.5g
On passing electricity of (2×96500C);Cu deposited
=(63.5)×(1295.6C)(2×96500C)=0.426gZn2+(aq)+2e−2F(2×96500 C)→Zn(s)65.3g
Deposited Cu = 0.426g
Deposited Zn = 0.438g