Calculating K and _Go from Eocell
Problem: Lead can displace silver from solution:
As a consequence, silver is a valuable by-product in the industrial
extraction of lead from its ore. Calculate K and _Go at 25oC for this
reaction.
First calculate Eocell and then substitute the valueto find K and _Go.
Solution: Writing the half-reactions and their Eo values:
Pb(s) + 2 Ag+(aq) Pb2+(aq) + 2 Ag(s)
(1) Ag+(aq) + e- Ag(s) Eo = 0.80 V
(2) Pb2+(aq) + 2 e- Pb(s) Eo = - 0.13 V
Calculating Eocell: We double (1), reverse (2), and add the half-reactions:
2 Ag+(aq) + 2 e- 2 Ag(s) Eo = 0.80 V
Pb(s) Pb2+(aq) + 2 e- -Eo = 0.13 V
Pb(s) + 2 Ag+(aq) Pb2+(aq) + 2 Ag(s) Eocell = 0.93 V
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