Standard KCl Solutions for Calibrating Conductivity Cells
This table presents recommended electrolytic conductivity (κ)
values for aqueous potassium chloride solutions with molalities
of 0.01 mol/kg, 0.1 mol/kg and 1.0 mol/kg at temperatures from
0 °C to 50 °C. The values, which are based on measurements at the
National Institute of Standards and Technology, provide primary
standards for the calibration of conductivity cells. The measurements
at 0.01 and 0.1 molal are described in Reference 1, while
those at 1.0 molal are in Reference 2. Temperatures are given on
the ITS-90 scale. The uncertainty in the conductivity is about
0.03% for the 0.01 molal values and about 0.04% for the 0.1 and
1.0 molal values. The conductivity of water saturated with atmospheric
CO2
is given in the last column. These values were subtracted
from the original measurements to give the values in the
second, third, and fourth columns. All κ values are given in units
of 10–4
S/m (numerically equal to µS/cm).
The assistance of Kenneth W. Pratt is appreciated.
References
	 1. 	 Wu, Y. C., Koch, W. F., and Pratt, K. W., J. Res. Natl. Inst. Stand.
Technol. 96, 191, 1991.
	 2. 	 Wu, Y. C., Koch, W. F., Feng, D., Holland, L. A., Juhasz, E., Arvay, E.,
and Tomek, A., J. Res. Natl. Inst. Stand. Technol. 99, 241, 1994.
	 3. 	 Pratt, K. W., Koch, W. F., Wu, Y. C., and Berezansky, P. A., Pure Appl.
Chem. 73, 1783, 2001.
104
κ/S m–1
t/˚C 0.01 m KCl 0.1 m KCl 1.0 m KCl H2
O (CO2
sat.)
0 772.92 7 116.85 63 488 0.58
5 890.96 8 183.70 72 030 0.68
10 1 013.95 9 291.72 80 844 0.79
15 1 141.45 10 437.1 89 900 0.89
18 1 219.93 11 140.6 ­— 0.95
20 1 273.03 11 615.9 99 170 0.99
25 1 408.23 12 824.6 108 620 1.10
30 1 546.63 14 059.2 118 240 1.20
35 1 687.79 15 316.0 127 970 1.30
40 1 831.27 16 591.0 137 810 1.40
45 1 976.62 17 880.6 147 720 1.51
50 2 123.43 19 180.9 157 670 1.61
5-74