14.15a [ENDORSED]

[Lucia H 2L]

AgBr(s) <--> Ag+(aq) + Br-(aq)

anode: AgBr(s) + e- --> Ag(s) + Br-(aq)
cathode: Ag+(aq) + e- --> Ag(s)

Where did these half reactions come from? Shouldn't the anode be losing electrons? Also, where is the AgBr in the cathode equation?

[Chem_Mod]

First, identify which component is oxidized and which is reduced by assigning oxidation numbers.

Then, look up the relevant half-reactions in Appendix 2B that match the half-reactions of oxidation and reduction you just identified.

If the cell is to be galvanic (AKA voltaic, spontaneous) then E°_cell must be positive. Assign the half-reaction with the lowest (most negative) standard reduction potential to the cathode.

[904676178]

First, identify which component is oxidized and which is reduced by assigning oxidation numbers.

Then, look up the relevant half-reactions in Appendix 2B that match the half-reactions of oxidation and reduction you just identified.

If the cell is to be galvanic (AKA voltaic, spontaneous) then E°_cell must be positive. Assign the half-reaction with the lowest (most negative) standard reduction potential to the cathode.

I am somewhat confused about this question as well, isn't the half-reaction with the lowest most negative standard reduction potential supposed to be assigned to the anode? or are we using the (most negative) lowest standard reduction potential and assigning it to the cathode because it is a non-spontaneous reaction?

[Chem_Mod]

Vasiliki gives a good explanation on choosing your anode and cathode for this problem. See the answer here: viewtopic.php?f=140&t=28135&p=86714&hilit=agbr&sid=d0dd8e815892f0d08cafc4fba831ff83#p86714