Metrohm 765 Dosimat User Manual
Page 20
2.2. Modes
765 Dosimat
16
Since the volume of the solvent V
0
is dispensed in the operational method of the CNT D
mode, higher concentrations require a correction factor which takes the difference
between V
0
and V (volume of the solution) into consideration:
V
0
f = —–
V
This factor can be determined with the Dosimat in the DOS mode:
A solution of the desired concentration is prepared in the conventional manner in a
volumetric flask by dispensing the solvent with the aid of the Dosimat up to the mark of
the flask (V
0
). If the volume V of the volumetric flask is inputted in the calculation
parameter "s", the factor f is calculated directly by the Dosimat and appears on the
display.
The factor f determined in this manner holds for the appropriate substance/solvent pair in
the measured concentration range with the possibility of linear extrapolations up to
concentrations of ca. 1 mol/L.
Several correction factors are shown in the following table:
Concentration c
Substance/solvent
0.05
mol/L
0.1 mol/L 1 mol/L
Potassium hydrogen
phthalate/water
0.999 0.998 0.982
Na
2
EDTA·2H
2
O/water 0.991
0.981
-
NaCl/water 0.999
0.998
0.982
KNO
3
/water 0.998
0.997
0.960
CuSO
4
5H
2
O/water 0.995
0.992
0.904