Galvanic Cell Studies Involving Calcium Carbide Solutions

Abstract

The galvanic cell Fe[C](s) I CaC2, CaCl2(,) [ Cos)has been studied in detail in the temperature range 800~176 using electrodes containing carbon at different activity levels. Calcium metal, the electroactive species, is present in the electrolyte by virtue of the heterogeneous equilibrium CaC2(soln) ~ Ca(sore) + 2C(electvode or~ruclble)

Galvanic Cell Studies on Ionic Carbide and Nitride Solutions in Molten Salts

“…As molten salt electrolytes containing CaC2 are known to be partial electronic conductors (3,8), the expression for the cell voltage should include a correction term involving the electron transport number (18). This partial electronic conductivity could be in addition to a simple dissolution process at the origin of the gradual depletion of Ca from the Ca-Li electrode observed in this work.…”

“…Galvanic cells using CaC2 solutions in molten salts as electrolyte have been studied by previous authors (1-3) with unsatisfactory results as regards the possibility of determining accurately the carbon activity in iron electrodes. The reason for this lack of accuracy has been ascribed to the existence of electronic conductivity in the melt (3,4) as a consequence of the presence of calcium resulting from the establishment of the following equilibrium CaC2 (melt) ~ Ca (melt) -5 2C (s) [1] Most of the previous authors (1,3) have used pure synthetic CaC2 PrePared from the elements at a temperature near 1000~ and the physicochemical behavior of molten salt solutions prepared with the pure synthetic CaC2 seems to be quite different from that obtained with technical grade carbide. In fact, anodic voltametric curves (5) and chronopotentiometric studies (6) carried out in solutions prepared with synthetic CaC2 show, respectively, two waves and two transition times, the first attributed to the oxidation of calcium and the second to the oxidation of carbide ion.…”

Electrochemistry—I

“…244 Experiments have been carried out with LiCl-CaC12 or LiCl-LiF melts in iron or mild steel crucibles at 700°C to study the behavior of dissolved calcium carbide or lithium nitride. 245 These materials are suitable also for the salts containing dissolved metal as in the preparation of the alkali metals. 123 The corrosion studies on various types of container materials in molten salt mixtures (NaCl-KCl, LiCl, NaN03, KN03 , Na2S04) have been carried out by Venkatasetty and Saathoff 247 -it has been shown that the presence of alkali nitrates considerably reduces the corrosion rate of iron or mild steel, an effect which is attributed to the passivating nature of the nitrate ions.…”

Molten Salt Techniques

“…244 Experiments have been carried out with LiCl-CaC12 or LiCl-LiF melts in iron or mild steel crucibles at 700°C to study the behavior of dissolved calcium carbide or lithium nitride. 245 These materials are suitable also for the salts containing dissolved metal as in the preparation of the alkali metals. 123 The corrosion studies on various types of container materials in molten salt mixtures (NaCl-KCl, LiCl, NaN03, KN03 , Na2S04) have been carried out by Venkatasetty and Saathoff 247 -it has been shown that the presence of alkali nitrates considerably reduces the corrosion rate of iron or mild steel, an effect which is attributed to the passivating nature of the nitrate ions.…”