Electrode
Causes the ion in to measure in the solution the
movement electric field is by produces with the solution direct
contact two electrodes. This must the material which corrodes by
the anti- chemistry make to the potential electrode. Actual
center after the material which commonly used arrives has the titanium
and so on. The potential electrode is composed which by two
electrodes was called 为尔 the fatigue executes (Kohlrausch) the
electrode.
The conductivity survey needs to clarify two aspects. Is
the solution electric conductance, another is in the solution the 1/A
geometry relations, the electric conductance may through the electric
current, the voltage survey obtain. This survey principle in now
directly demonstrated in the measuring instrument obtains the
application.
But K= L
A
A - potential electrode effective pole plate
L - two pole plates distances
This value is called the electrode constant. Has
the uniform electric field in the electrode between in the situation,
the electrode constant may pass
Crosses the geometry size to figure out. When two
area are the 1cm2 square shape pole plates, when between is separated
by 1 cm composition electrode, this electrode constant
K=1cm-1. If obtains electric conductance value G=1000 mu S with
this to the electrode, then is measured the solution conductivity
K=1000 mu S/ cm.
In ordinary circumstances, electrode often shaping unit non-
uniform electric field. This time, the electrode constant must
use the standard solution to carry on the determination. The
standard solution generally all uses KCl solution this is because in
the KCl conductivity different temperature and the density situation
is extremely stable, accurate. 0.1 mol/l KCl
solution in 25 ?time conductivity is 12.88mS/CM.
The so-called non- uniform electric field (also is called as
stray field, 漏泄 field) does not have the constant, but is concerns
with the ion type with the density. Therefore, a pure stray
field electrode is the most too bad electrode, it cannot satisfy the
width through a calibration the survey scope need. `
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