Potentials Of Various Reference Electrodes; Principle Of The Conductivity Measurement - Chauvin Arnoux MPC 350 Notice De Fonctionnement

4. POTENTIALS OF VARIOUS REFERENCE
If the work is done at a temperature other than 25°C or with a reference electrode
other than (Ag, AgCl, 1 mol.L
indicated on the label. Here is the table applicable to the Michaelis solution:
Potential difference between the platinum electrode and the reference electrode
immersed in the diluted Michaelis solution (see label)
Reference
(Ag, AgCI,
electrode
KCI,
1mol.L
Temperature
15°C 164mV
20°C 155mV
25°C 146mV
30°C 135mV
UNCERTAINTY ± 4mV
5. PRINCIPLE OF THE CONDUCTIVITY
The electrical conductance, G, of a liquid depends on the geometry of the volume
of liquid involved. It is the reciprocal of the resistance, R. It is expressed in
Siemens (S).
The conductivity
per centimetre. The conductivity
conductivity of a column of liquid 1cm long having a cross-sectional area of 1cm
The conductivity of an electrolyte depends only on its nature and its concentration.
MPC 350 Multiparameter meter
ELECTRODES
-1
KCl), the potential E read will be different from that
(Ag, AgCI, (Ag, AgCI,
KCI, KCI,
-1 -1
) 3mol.L ) 3,5mol.L
192mV
183mV
174mV
165mV
± 4mV
MEASUREMENT
G = 1 / R ; 1 S = 1 Ω
γ
is the reciprocal of the resistivity,
γ
γ
ρ
= 1 /
(Ag, AgCI,
KCI,
-1
) saturé)
195mV 198mV
187mV 191mV
177mV 183mV
168mV 175mV
± 4mV ± 4mV
is a specific characteristic of a liquid. It is the
-1
; 1 S.cm = 1 (Ω.cm)
(Hg, Hg , (Hg, Hg
2
CI KCI CI KCI
2 2
-1
1mol.L ) saturé)
121mV 156mV
111mV 147mV
99mV 138mV
87mV 128mV
± 4mV ± 4mV
-1
ρ
. It is expressed in Siemens
-1
English
(Hg, Hg ,
2
,
2
SO K
4 2
SO
4
-1
1mol.L )
-276mV
± 4mV
2
.
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