Electrolytic conductivity: a reference system for aqueous solutions.

To establish a system for the measurement of electrolytic conductivity in aqueous solutions with traceability to the SI, a cell has been developed with a removable central section providing an accurate determination of the geometrical constant. As the concentration unit mass/mass, based and referred to the amount of substance in the SI, is recommended by international organisations, 0.1 molal KCl samples have been prepared and analysed. Results over a temperature range from 20 degrees C to 35 degrees C are presented. The main sources of error have been estimated and relative uncertainty has been assessed to remain at the level of 0.6%. Satisfactory agreement is observed when the results are compared with the reference values available from literature.