spacer spacer Go to Kaye and Laby Home spacer
spacer
spacer spacer spacer
spacer
spacer
spacer
spacer spacer

You are here:

spacer

Chapter: 3 Chemistry
    Section: 3.9 Electrochemistry
        SubSection: 3.9.1 Standard solutions for calibrating conductivity vessels

spacer
spacer

spacer

« Previous Section

Next Subsection »

Unless otherwise stated this page contains Version 1.0 content (Read more about versions)

Version 1.1
Updated: 2 October 2012
Previous versions

3.9 Electrochemistry

3.9.1 Standard solutions for calibrating conductivity vessels

The primary standards for conductivity for KCl solutions were established by Jones and Bradshaw (1933) using the demal unit for concentration and the international ohm. In 1948 the international ohm was replaced by the absolute ohm as the unit of resistance. Recently, the standards have been redetermined at NIST (formerly NBS) in the USA using a cell with well-defined geometry (Wu, Pratt and Koch, 1989). It is proposed that the demal (D) unit be replaced eventually by molality and the measurements will be extended over the range 0–60 °C. There is good agreement between the redetermined values and corrected Jones and Bradshaw values.

Conductivity of potassium chloride solutions at 25 °C

g KCl per kg solution
in vacuo

      κ/(S cm−1)

7.474 58 (0.1 D)

     0.012 854

0.745 819 (0.01 D)

     0.001 408 6

7.455 10 (0.1 m)

     0.012 821 7

0.745 510 (0.01 m)

     0.001 407 9

Units: m/mol kg−1 H2O;  D/mol kg−1 solution.


The following equation, which gives the molar conductivity of aqueous potassium chloride solution at 25 °C in the range 0.01 mol dm−3 < c < 0.10 mol dm−3, is also useful for cell calibration (Chiu and Fuoss, 1968):

Λ 

=

149.879 − 94.84c1/2 + 58.65c log c + 220.9c − 228.9c3/2  S cm2 mol-1

A.K. Covington
R. J. C. Brown

spacer


spacer
spacer
spacer spacer spacer

Home | About | Table of Contents | Advanced Search | Copyright | Feedback | Privacy | ^ Top of Page ^

spacer

This site is hosted and maintained by the National Physical Laboratory © 2017.

spacer