Proposed New Electrolytic Conductivity Primary Standards for KCl Solutions

An absolute determination of aqueous electrolytic conductivity has been made for 0.01 molal (m) and 0.1 m potassium cliloride solutions, over the temperature range of 0 to 50 °C in 5 degree intervals. A cell with a removable center section of accurately known length and area was used for the measurements. Values were adjusted to be in conformity with the ITS-90 temperature scale. The overall uncertainty over the entire temperature range is estimated to be 0.03%. Values at 25 °C for 0.01 and 0.1 m are 0.00140823 and 0.0128246 S/cm, respectively. It is proposed that these values be adopted as primary standards for aqueous electrolytic conductivity, replacing the demal scale.