In: Chemistry
A voltaic cell is constructed that is based on the following reaction: Sn2+(aq)+Pb(s)→Sn(s)+Pb2+(aq).
1. If the concentration of Sn2+ in the cathode compartment is 1.50 M and the cell generates an emf of 0.25 V , what is the concentration of Pb2+ in the anode compartment?
2.If the anode compartment contains [SO2−4]= 1.00 M in equilibrium with PbSO4(s), what is the Ksp of PbSO4?
1)
Lets find Eo 1st
from data table:
Eo(Pb2+/Pb(s)) = -0.126 V
Eo(Sn2+/Sn(s)) = -0.13 V
As per given reaction/cell notation,
cathode is (Sn2+/Sn(s))
anode is (Pb2+/Pb(s))
Eocell = Eocathode - Eoanode
= (-0.13) - (-0.126)
= -0.00400 V
Number of electron being transferred in balanced reaction is 2
So, n = 2
Use:
E = Eo - (0.0592/n) log {[Pb2+]/[Sn2+]}
0.25 = -0.00400 - (0.0592/2) log ([Pb2+]/1.5)
log ([Pb2+]/1.5) = -8.581
([Pb2+]/1.5) = 2.624*10^-9
[Pb2+] = 3.94*10^-9 M
Answer: 3.94*10^-9 M
2)
PbSO4 (s) <—> Pb2+ (aq) + SO4 2- (aq)
Ksp = [Pb2+][SO42-]
Ksp = (3.94*10^-9)*(1.00)
Ksp = 3.94*10^-9
Answer: 3.94*10^-9