Na2ZnOH4

Na2ZnOH4, often written as sodium zincate, is an inorganic salt that comprises the zincate anion [Zn(OH)4]2- with two sodium counterions. The formula is commonly represented as Na2[Zn(OH)4]. In the solid state the compound consists of a lattice of Na+ ions and tetrahedral [Zn(OH)4]2- units; in aqueous solution it behaves as a highly basic zincate species.

Preparation and structure

Sodium zincate is typically prepared by reacting zinc oxide or metallic zinc with hot concentrated sodium hydroxide solution, followed by crystallization. The resulting solid can form hydrates depending on conditions. In solution, the tetrahedral Zn(II) center is coordinated by four hydroxide ligands, yielding the [Zn(OH)4]2- anion.

Properties

The compound is a white to colorless, hygroscopic solid that is highly soluble in water and strongly basic (pH well above 12 in solution). It is stable under basic conditions but can hydrolyze or decompose upon heating or prolonged exposure to moisture, forming zinc hydroxide or oxide species. It readily reacts with acids to give Zn2+ salts and water. Exposure to CO2 over time can lead to carbonate or hydroxy-carbonate species.

Applications

Sodium zincate serves as a source of zincate for inorganic synthesis and certain specialized processes that require zincate species. It can be used as an intermediate in the preparation of other zinc-containing hydroxide or oxide materials and, in some contexts, in plating or surface-treatment chemistries.

Safety

The compound is caustic and corrosive. It can cause skin and eye irritation; handle with appropriate protective equipment and work in a well-ventilated area. Avoid contact with acids and reduce exposure to moisture to prevent vigorous reactions.

References

Entries on sodium zincate and zincate chemistry in inorganic chemistry handbooks provide detailed preparation, structure, and reaction data.