Yokogawa PH72 Personal pH/ORP Meter - Manual (Page 78)

IM 12B03D02-01E
9-11
9. Technical Information
Obtained from equation 9.10, the potential of the Ag/AgCl electrode filled with a 3.3
mol/l KCl solution, E'
AgCl
, has the temperature characteristic for the standard hydrogen
electrode as shown in Figure 9.12.
To convert E'
AgCl
to the value for the standard hydrogen electrode,
E : oxidation-reduction potential when reference electrode is SHE
E : oxidation-reduction potential when reference electrode is Ag/AgCl
electrode filled with 3.3 mol/l KCl solution
E : potential of Ag/AgCl electrode filled with 3.3 mol/l KCl solution (vs SHE)
E : liquid junction potential (average liquid junction potential between KCl
and test solution is approximately 3 mV)
E
؍ E ؉ E ؉ E [mV]
SHE
SHE
j
(9.11) '
AgCl
'
AgCl
j
3.3mol/l KCl-Ag/AgCl Electrode P
otential
(vs SHE), E' [mV]
60 40 20 0
Temperature [
؇
C]
150
200
250
F0912.EPS
AgCl
Figure 9.12 Temperature Characteristic of Potential of Ag/AgCl
Electrode with 3.3 mol/l KCl, E'
AgCl
(vs SHE)