Electrolytic Behavior of Elements of the Group VIa in the Periodic System. II. Conductometric Studies on the Chromate, Molybdate and Tungstate Ions

Abstract

Abstract (1) Conductance measurements of sodium chromate, molybdate and tungstate solutions were carried out by using a Du Mont 208 type cathode-ray oscillograph as a detector of the Kohlrausch bridge setting. (2) Equivalent conductivities of chromate, molybdate and tungstate at varying dilutions were measured at 25°C., but the limiting value of the equivalent conductivity of each salt at infinite dilution could not be estimated by the usual way, owing to the hydrolysis of these salts. (3) The similarity between molybdate and tungstate as well as the dissimilarity between chromate and each of the two others were confirmed also in the present investigation. (4) The difference Λ1024–Λ32 was found to be approximately equal to 2×10 for these sodium salts. It seems to indicate that either molybdic or tungstic or even chromic acid may be a kind of weak dibasic acid if Ost-wald’s rule is applicable. (5) Besides two breaks at the XO4−− to H+ mol-ratios, 6:7 and 6:9 were found in the conductometric titration curves of molybdate and tungstate, a new sharp break at the molratio 12:11 was observed prominently in the titration curves of molybdate but fairly in those of tungstate. (6) A break at the mol-ratio, 6:8, which was reported in the previous paper, was found also in the titration curves of tungstate.