Electrometric investigations of an acid-thiomolybdate system and the formation of polyanions

Abstract

The acidification of sodium thiomolybdate with progressive addition of HCl has been studied by pH and conductometric measurements, which have revealed the formation of three different polymerized species, viz. (MO₄S₁₅)^6-, (MO₂S₇)^2-, and (Mo₄S₁₃)^2- at pH ranges 7.5-8.5, 4.2-5.3, and 2.8-3.3 respectively. It was observed that at higher hydrogen ion concentration (pH < 2.5), thiomolybdate decomposes into hydrated molybdenum trisulphide, MoS₃,H₂O.