In: Chemistry
QUESTION 5
An electrochemical cell is based on the following two
half-reactions:
Ox: Pb(s)→Pb2+(aq, 0.21 M
)+2e−
Red: MnO−4(aq, 1.80 M )+4H+(aq,
1.5 M )+3e−→ MnO2(s)+2H2O(l)
Compute the cell potential at 25 ∘C.?
Ox:
3Pb(s)→3Pb2+(aq)+6e−
E 0 = 0.13v
Red: 2MnO4^-(aq)+8H+(aq)+6e−→
2MnO2(s)+4H2O(l)
E0 = 1.68v
-------------------------------------------------------------------------------------------
3Pb(s) + 2MnO4^- (aq)+ 8H^+(aq) ------------> 3Pb^2+ (aq) + 2MnO2(s) + 4H2O(l) E0cell = 1.81v
n = 6
Ecell = E0cell - 0.0592/n logQ
= 1.81 - 0.0592/6 log[Pb^2+]^3/[MnO4^-]^2 [H^+]^8
= 1.81 - 0.00986log(0.21)^3/(1.8)^2*(1.5)^8
= 1.81- 0.00986log0.0001115
= 1.81-0.00986*-3.9527
= 1.849v >>>>answer