Physical Review Volume 4 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1897 Excerpt: ...other chloride in the same concentration. While it is impossible to compute the theoretical value of the depression on the basis of the dissociation theory, since measurements on the conductivity of these solutions are wanting, it is, however, a striking fact that if it be assumed that the salt at the concentration m = 0.01 be completely dissociated, and that each molecule splits up into the maximum number of five parts, Sn-Cl-Cl-Cl-Cl, we would then have for the molecular depression only 5 x 1.89 or 9.45, while the observed value is 12.61. Obviously the depression is not to be explained in this way. It however suggests itself that the SnCl4 does not exist at all in aqueous solutions, but that it assumes at once the properties of a mixture of SnCl2 and 2 HC1, in solution. No value for the depression of the freezing-point by SnCl2 has been found; but assuming that it is about that of CdCl2 and ZnCl2, as observed by Jones, i.e. 5.20, and taking the observed value for HC1, i.e. 3.61, we have for the depression due to SnCl4, 5.20+ 2(3.61), or 12.42. This is very nearly the observed value. It should be said that many vain attempts were made to prepare solutions of SnCl2, sufficiently free from SnCl4, to enable the freezing-points to be measured. The purpose was to measure the depressions in a solution of SnCl2 at m = 0.01, and then add in succession a jfo grammolecule of HC1. Thus measurements would be made on SnCl2, m = 0.01, SnCl2 + 1 HC1, in = 0.01, SnCl2 + 2 HC1, m = 0.01, SnCl2 + 3 HC1, m = 0.01, as was done in the cases of the phosphates, p. 288. This would have decided experimentally whether the suggestion just made in regard to the nature of SnCl4 in solution is tenable. I hope to return to this difficulty in the near future. It may be well to call atten...