ELMETRON CX-401, User Manual, Page: 69 / 120

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19. SIMPLIFIED WAY OF DETERMINING THE
αααα
COEFFICIENT
The knowledge of
α
coefficient has a crucial significance during
measurements in temperatures different than the reference temperature.
This coefficient is changing together with the temperature and concentration.
Table 4 contains values of
α
coefficient in 25 oC for a few compounds with
determined weight concentration.
Table 4
compound
Weight
concentration
αααα
coefficient
HCl 10 % 1.56
KCl 10 % 1.88
H
2
SO
4
50 % 1.93
NaCl 10% 2.14
HF 1.5 % 7.20
HNO
3
31 % 1.39
Table 5 contains rough values of
α
coefficient for KCl and NaCl depending
on the temperature and concentration of the measured liquid.
Table 5
αααα
temperature coefficient
KCl solution
temp.
`0
C
0,01M 0,1M 1,0M
saturated
NaCl
5 2,68 2,68 2,39 2,77
10 2,45 2,36 2,20 2,53
15 2,27 2,19 2,04 2,38
20 2,11 2,06 1,89 2,21
25 1,91 1,86 1,75 2,03
30 1,80 1,77 - 1,91
Use the value of the
α
coefficient determined for the reference temperature
to which the meter calculates the result.
It may be assumed that the
αααα
coefficient is constant in the range ±5
0
C
from the reference temperature.