Measurement of iodine vapour pressures in the range 10 4-10 0 Pa by use of γ-AgI as the solid electrolyte in galvanic cells

Abstract

A galvanic cell is presented to measure equilibrium iodine partial pressures in the Te-I system. The cell arrangement allows the determination of rather low vapour pressures. The cell performance at higher iodine pressures was verified by measuring the e.m.f. of the formation reaction of AgI from the elements in the temperature range from 300 to 420 K, which is above the melting point of iodine. γ-AgI rather than β-AgI was the solid electrolyte used in these investigations. An attempt was made to estimate the lower limit of measurable iodine activities.