Na2TeO3

Na2TeO3, commonly called sodium tellurite, is an inorganic salt composed of two sodium cations and the tellurite anion TeO3^2−. In this salt, tellurium is in the +4 oxidation state. The solid is a white, odorless crystalline substance that is readily soluble in water, yielding alkaline solutions.

Preparation and structure: Na2TeO3 can be prepared by treating tellurium dioxide TeO2 with hot aqueous sodium hydroxide: TeO2 + 2 NaOH → Na2TeO3 + H2O. In solution, the TeO3^2− ion features Te in +4 and a distorted trigonal pyramidal geometry; in the solid, the ions form a three-dimensional lattice.

Chemistry: The tellurite ion is susceptible to redox changes; Na2TeO3 can be oxidized to tellurate (TeO4^2−) under strong oxidants, and reduced to elemental tellurium or TeO2 by reducing agents. It also acts as a mild reducing agent for certain metal ions.

Applications: Sodium tellurite serves as a source of TeO3^2− in inorganic synthesis and analysis, and is used to prepare other tellurium compounds. It has historical use in qualitative inorganic analyses and in some microbiological assays as part of selective media.

Safety: Tellurite compounds are toxic and should be handled with care. They can be corrosive and pose health and environmental hazards; dispose as hazardous waste according to regulations.