Glossary Multi 9310
96 ba75937e03 12/2011
17 Glossary
pH/ORP
Conductivity
Asymmetry see zero point
Electromotive force of
an electrode
The electromotive force U of the combination electrode is the measur-
able electromotive force of an electrode in a solution. It equals the
sum of all the galvanic voltages of the combination electrode. Its
dependency on the pH results in the electrode function, which is char-
acterized by the parameters, slope and zero point.
Junction The junction is a porous body in the housing wall of reference elec-
trodes or electrolyte bridges. It arranges the electrical contact
between two solutions and makes the electrolyte exchange more dif-
ficult. The expression, junction, is also used for ground or junction-
less transitions.
ORP voltage The ORP is caused by oxidizing or reducing substances dissolved in
water if these substances become effective on an electrode surface
(e. g. a gold or platinum surface).
pH value The pH value is a measure of the acidic or basic effect of an aqueous
solution. It corresponds to the negative decadic logarithm of the molal
hydrogen ions activity divided by the unit of the molality. The practical
pH value is the value of a pH measurement.
Potentiometry Name of a measuring technique. The signal (depending on the mea-
sured parameter) of the electrode is the electrical potential. The elec-
trical current remains constant.
Slope The slope of a linear calibration function.
Zero point The zero point of a pH combination electrode is the pH value at which
the electromotive force of the pH combination electrode at a specified
temperature is zero. Normally, this is at 25 °C.
Cell constant, C Characteristic quantity of a conductivity measuring cell, depending on
the geometry.
Conductivity Short form of the expression, specific electrical conductivity.
It corresponds to the reciprocal value of the resistivity.
It is a measured value of the ability of a substance to conduct an elec-
tric current. In water analysis, the electrical conductivity is a dimension
for the ionized substances in a solution.
Reference
temperature
Fixed temperature value to compare temperature-dependent mea-
sured values. For conductivity measurements, the measured value is
converted to a conductivity value at a reference temperature of 20 °C
or 25 °C.
Resistance Short name for the electrolytic resistivity. It corresponds to the recip-
rocal value of the electrical conductivity.
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