Consider the electrochemical cell:
Volts
1.0 M KNO3
Ag Fe
1.0 M Ag NO3 1.0 M Fe (NO3)2
a) Towards which half-cell do the NO3
−
( ) aq in the salt bridge initially move? and explain why its the Fe electrode. also explain how each is the anode or cathode
The NO3- ions in the salt bridge initially move towards the Fe electrode. This is because the Fe electrode has a higher electron affinity (tendency to gain electrons) compared to the Ag electrode.
In an electrochemical cell, the species that gains electrons is reduced and acts as the cathode, while the species that loses electrons is oxidized and acts as the anode. In this case, Fe (Fe2+) is reduced and acts as the cathode, while Ag is oxidized and acts as the anode.
At the Fe electrode, Fe2+ ions gain electrons and are reduced according to the following half-reaction:
Fe2+(aq) + 2e- -> Fe(s)
At the Ag electrode, Ag atoms lose electrons and are oxidized according to the following half-reaction:
Ag(s) -> Ag+(aq) + e-
Overall, the Fe electrode is the cathode because it gains electrons and the Ag electrode is the anode because it loses electrons. The NO3- ions in the salt bridge move towards the Fe electrode to balance the charge as the Fe2+ ions are being reduced.