The Potential of the Rubidium Electrode.

Abstract

The method used by Lewis and Kraus, and Lewis and Keyes for the determination of the electrode potential of sodium,4 potassium6 and 1

Potential Differences Between the Alkali Metals and Their Amalgams

“…The emf value of 1.0766V for Rb(Hg)(XRb ----0.00539) agrees reasonably with the corresponding value of 1.0745V reported by Lewis and Argo (7) for an identical amalgam composition, and with 1.077V calculated from the aqueous solution measurements of Longhi, Mussini, and Osimani (16).…”

Thermodynamic Properties of the Alkali Metals in Aluminum Chloride‐Propylene Carbonate Solution

“…--In addition, emf's of the cell M(s)/MCI(m), AICls(lm),PC/M(Hg) were also measured. The concentrations of the Na, K, and Rb amalgams were adjusted to the exact concentrations of the amalgams used by Lewis and his co-workers (18)(19)(20)(21). This was done in order to be able to make comparison with emf data for the single amalgam concentrations listed in the literature.…”

“…This is not the case in acetonitrile, N-MF, and water, where lithium has the highest oxidation potential (see Table IX). It may be proper to quote the prediction made by Lewis and Argo in 1915 (21) concerning the peculiarity of the order of the standard potentials in the alkali metal series: "The potentials of the alkali metals follow a curious order, namely, lithium, rubidium, potassium, and sodium. It is interesting, however, to observe that this is the order of the heats of formation of the several ions in aqueous solution.…”

“…In order to illustrate this fact, the heat of formation of the chlorides of the four metals in aqueous solution are: 102, 101, 101, 96 kcal/ mole for LiC1, RbC1, KC1, and NaC1, respectively. The heat of formation of aqueous cesium chloride is given as 105 kcal/mole, and if this figure is correct, we might predict the potential of cesium to be higher than any of the other alkali metals" (21). However, this prediction did not materialize when 14 years later Bent, Forbes, and Forziani (23) obtained the normal electrode potential of cesium, E ~ -----2.923 volts, "...very close to the corresponding value for rubidium, but still 34 millivolts below that for lithium.…”