Effect of Pressure on the Activation Energy of Electrical Conduction in Aqueous Solution

The specific conductances of aqueous KCl, KOH, and HCl solutions have been measured as functions of hydrostatic pressure and temperature over the ranges 5° to 45°C and 1 to 6900 bars. The activation energy for the conductance of KCl solutions varies in roughly the same way with pressure as does the viscosity of the medium. The activation energy for the conductance of HCl solutions does not vary with pressure in the same way as do KCl solutions and the viscosity because the principal contribution to the conductance arises from a Grotthuss-type protonic transfer rather than from simple translational ionic movement. At lower pressures the rotation of water molecules appears to be the rate-controlling step, but above about 1380 bars the proton jump becomes rate determining.