3 Nernst
Nernst
Nernst
Nernst
Nernst
Equation
Equation
Equation
Equation
Equation
We have assumed in the previous section that the concentration of all
the species involved in the electrode reaction is unity This need not be
always true Nernst showed that for the electrode reaction:
Mn+(aq) + ne–® M(s)
the electrode potential at any concentration measured with respect to
standard hydrogen electrode can be represented by:
(
)
(
)
+
+
=
n
n
o
M
/ M
M
/ M
E
E
 –  RT
nF  ln [M]
[M
]
n+
but concentration of solid M is taken as unity and we have
(
)
(
)
+
+
=
n
n
o
M
/ M
M
/M
E
E
 – 
RT
nF  ln
n+
1
[M
]
(2 8)
(
)
n+
o
M
/ M
E
has already been defined, R is gas constant (8