Calcium Subchloride, CaCl or Ca₂Cl₂

In carrying out experiments on the preparation of calcium by electrolysis of the fused chloride, a product regarded as a subchloride, Ca₂Cl₂, has sometimes been obtained. Wohler and Rodewald2 obtained the subchloride by a method similar to that which they employed for the subfluoride. Calcium and calcium chloride in equivalent proportions were heated together for 24 hours, at 900°-1000° C., in steel cylinders of 9 c.c. capacity. This was followed by rapid quenching in solid carbon dioxide. The metallic calcium was removed by floating off in ethyl iodide, and bromoform was used to separate the subchloride from the chloride. Red-violet crystals, which recalled Borchers and Stockem's product, were obtained. The temperature which must be reached before the formation of subchloride can take place, was found to be about 800° C. This explains why, in the electrolysis of calcium chloride, the production of the subchloride can be avoided by keeping the temperature below 800° C.

When calcium subchloride is acted upon by water it gives calcium chloride, calcium hydroxide, and hydrogen.

Ca₂Cl₂ + 2H₂O = CaCl₂ + Ca(OH)₂ + H₂.