Textbook Problem

The black silver sulfide discoloration of silverware can be removed by heating the silver article in a sodium carbonate solution in an aluminum pan. The reaction is

$3{\text{Ag}}_2\text{S}\left(s\right)+2\text{Al}\left(s\right)\rightleftharpoons 6\text{Ag}\left(s\right)+3{\text{S}}^{2-}\left(aq\right)+2{\text{Al}}^{3+}\left(aq\right)$

a. Using data in Appendix 4, calculate ∆G°, K, and  for the above reaction at 25°C. [For Al³⁺(aq), $\Delta G_{\text{f}}^{°}$ = −480. kJ/mol.]

b. Calculate the value of the standard reduction potential for the following half-reaction:

$2{\text{e}}^{-}+\text{Ag}2\text{S}\left(s\right)\to 2\text{Ag}\left(s\right)+\text{S}{2}^{-}\left(aq\right)$