Hach-Lange POLYMETRON 83xx User Manual - Manual (Page 10)

2 E LECTRODES C ONDUCTIVITY P ROBE - I NSTRUCTION M ANUAL
Page 6 09/2010 621=183=000 Issue B
E, potential
R, resistance of the dipole such as:
the resistance of a homogenous
environment depends on the geometry of
the resitivity (characteristic of the material):
R = r. l/S where r = R/K (
Ω.cm) where
R
K
C
=
(S.cm
-1
)
K depending solely on the geometry of the
probe is (in the case of the two flat electrodes
face to face) the relation between the distance
separating the electrodes divided by their
surfaces and expressed in cm
-1
.
I= E/R= C.E/K
Influence of the temperature
The conductivity of a solution depends both on
the ionic concentration and the mobility of these
ions (size, weight, charge, viscosity). The
temperature of the solution has an influence on
these two factors (the temperature favours the
dissociation of the molecules and therefore the
ionic concentration, and increases the mobility).
In order to allow the comparison between
measurements made at different temperatures,
this measurement needs to be brought back to
a reference temperature (generally 25 °C).