Consider two cels, the first with Al and Ag electrodes, and the second with Zn a
ID: 1040005 • Letter: C
Question
Consider two cels, the first with Al and Ag electrodes, and the second with Zn and Ni electrodes, each in appropriate 1.00 M solutions of their ions a) If connected as voltaic cells in series, which two metals are plated, and what is the total potential? A(S) 2 Ag(s) Zn(s) Ni(s) Number b) If connected such that one cell acts as a battery to power the other as an electrolytic cell, which two metals are plated, and what is the total potential? AI(s) Ag(s) Zn(s) Ni(s) Number E1.98 c) If 4.70 g of metal is plated in the voltaic cell, how much metal is plated in the electrolytic cel? Number 5.14Explanation / Answer
the standard potential of the given four metals are: (values may change from reference to reference)
Zn+2 + 2e =Zn E0= -0.76 V
Ni+2 + 2e=Ni E0=-0.25 V
Al+3 + 3e =Al E0 = -1.66 V
Ag+ + e= Ag E0= +0.8 V
Now for part a, the metals which have higher reduction potential will get electron and the electroplating will occur to them therefore for first cell Al and Ag, Ag has more reduction potential so it will reduce and get collected over as Ag plating over the electrode
for second cell , due to the same reason Ni will be plated when it is coupled with Zn.
Now , overall potential for first cell is = E1 =(1.66+ 3*0.8)/3 = 1.353 V
similarly E2= (2*0.76-2*0.25)/2=0.510 V
since both cells are in series thats why ENET = E1 + E2 = 1.353 +0.51=1.858 V
PART b ,
the cell which is acting as a battery will have the metal which is having more reduction potential will be forming layer over its own electrodes.
For the cell which is run by battery, the metal which will have lowertendency to reduce will form the layer.Hence the answer is Ag and Zn.
Also two cells can only be connected as a series network hence the net potential will now = E1-E2= 0.843. V
part C,
the cell with more E will act as battery therefore al and ag will act as battery therefore
The weight of metal plated on electrolytic cell will be as per faradays law i.e. ,
n1*(m1/M1)=n2*(m2/M2)
3*4.7/108=2*x/65
x=4.24g