The Effect of Pressure on the Electrical Conductance of Salt Solutions in Water

Abstract

New data are presented for the change with pressure of the equivalent conductance of the following $\frac{1}{100}$ normal salt solutions in water: at 30°C, HCl, LiCl, NaCl, KCl, RbCl, CsCl, NaF, NaBr, NaI, ${\mathrm{Na}}_2$S${\mathrm{O}}_4$, Na${\mathrm{C}}_2$ ${\mathrm{H}}_3$ ${\mathrm{O}}_2$, Ca${\mathrm{Cl}}_2$, Ba${\mathrm{Cl}}_2$, Th${\mathrm{Cl}}_4$, ${\mathrm{K}}_3$Fe(C${\mathrm{N})}_6$, ${\mathrm{K}}_4$Fe(C${\mathrm{N})}_6$; and at 75°C, all the above solutions excepting NaF and Th${\mathrm{Cl}}_4$. The pressure range at 30°C is 1-10,000 kg/${\mathrm{cm}}^2$, and at 75°C it is 1-11,000 kg/${\mathrm{cm}}^2$. It is pointed out that the observed maxima in the equivalent conductance can not be entirely caused by a change in the degree of dissociation of the ions with pressure. By using a well-known expression for the equivalent conductance at infinite dilution, and also by using the Debye-Hücklel formula, it is shown in each case that there must be a large change in the diameters of the ions due to the pressure if the theory is to agree with the data.