Chemistry Reference
In-Depth Information
2.7 Potentials in Electrochemical
Measurements
In the articles and topics dealing with organic
electrode reactions, there are many kinds of
potentials [8,9]. The following six kinds of
potentials are frequently used and hence we will
discuss them:
standard electrode potential
formal potential
peak potential
half-peak potential
half-wave potential
decomposition potential (onset potential).
If we know the standard state free energy
change, Δ
G
o
, for a chemical process, we can
calculate the standard electrode potential,
E
o
,
for an electrochemical reaction based on that
process using the relationship between Δ
G
o
and
E
o
. Thus the
E
o
is not the experimental value
but the calculated value. Therefore, even if the
electrode potential is measured using the SHE
under an equivalent state, the value measured
will deviate from the real
E
o
value to a small
degree. The value measured using the SHE
under an equivalent state is termed the formal
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