Question

What are the important features of the electrochemical series?

Answer 1

i. When coupled to a standard hydrogen electrode, the electrode system with the negative standard reduction potential values serves as the anode and the one with the positive values as the cathode.

ii. The tendency to gain electrons, or the tendency for reduction to occur, increases as one moves from the top of the series to the bottom.

The substance at the top of the series, the Li⁺ ion, has the least potential to be reduced when it is oxidised. Therefore, the weakest oxidising agent is the Li⁺ ion. However, as can be seen from the following, its reduced form, Li, will have the largest tendency to oxidise.

\[\ce{Li{^{+}_{(aq)}} + e- -> Li_{(s)}}\]; \[\ce{E^{\circ}_{{Li^{+}/{Li}}}}\]  = −3.05 V

\[\ce{Li_{(s)} -> Li{^{+}_{(aq)}} + e-}\]; \[\ce{E^{\circ}_{{Li/{Li^{+}}}}}\] = +3.05 V

Li thus will act as a very strong reducing agent. Any additional material placed behind it in the sequence will be able to be reduced by it.

iii. The tendency to lose electrons, or for oxidation to take place, rises as one moves up the series from the bottom.