Metrohm 765 Dosimat User Manual download pdf (Page 20)

2.2. Modes

765 Dosimat

Since the volume of the solvent V

is dispensed in the operational method of the CNT D

mode, higher concentrations require a correction factor which takes the difference

between V

and V (volume of the solution) into consideration:

f = —–

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

). 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

EDTA·2H

O/water 0.991 0.981 -

NaCl/water 0.999 0.998 0.982

KNO

/water 0.998 0.997 0.960

CuSO

O/water 0.995 0.992 0.904

1 2 ... 15 16 17 18 19 20 21 22 23 24 25 ... 65 66

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Metrohm 765 Dosimat User Manual Page 20