PHYSICO-CHEMICAL STUDIES OF COMPLEX ACID. PART I. DECOMPOSITION OF AMMONIUM MOLYBDATE WITH NaOH AND HCl

The decomposition by HCl of a molybdic acid salt with a weak base. (i.e. ammonium molybdate) has been studied electrometrically and otherwise and the results are compared with those of its salt with a strong base (i.e. sodium molybdate) under similar conditions. The nature of the decomposetions is shown to be the same in both cases, higher and higher polysalts being formed with increasing addition of HCl. But the rapid rise of conductivity and (H+) (hydrogen ion concentration) beyond the stage R4[O(MoO3)4] (R =Na or NH4) is considered to be due to the formation of an acid molybdete RH[O(OMoO3)2-4]. The action of NaOH on ammonium molybdate having the composition (NH4)2- O(MoO3)2.4] has been studied electrometrically and it is shown that the anion of this salt gradually brooks into a normal one [O(MoO3)] and then NH4+ ion is displaced from the salt by Na+ ion ; from the curves, NH4+ion can be estimated. The formation of higher polymolybdatos from normal one has been described in terms of electronic structure