Sodium zincate explained

Sodium zincate refers to anionic zinc oxides or hydroxides, depending on conditions. In the applications of these materials, the exact formula is not necessarily important and it is likely that aqueous zincate solutions consist of mixtures.^[1]

Hydroxyzincates

Solutions of sodium zincate may be prepared by dissolving zinc, zinc hydroxide, or zinc oxide in an aqueous solution of sodium hydroxide. Simplified equations for these complex processes are:

ZnO + H₂O + 2 NaOH → Na₂Zn(OH)₄

Zn + 2 H₂O + 2 NaOH → Na₂Zn(OH)₄ + H₂

From such solutions, one can crystallize salts of containing the anions Zn(OH)₄²⁻, Zn₂(OH)₆²⁻, and Zn(OH)₆⁴⁻. Na₂Zn(OH)₄ consists of tetrahedral zincate ion and octahedral sodium cations.^[2]
The salt Sr₂Zn(OH)₆ features zinc in an octahedral coordination sphere.

Oxozincates

Related oxides are also known such as Na₂ZnO₂,^[3] Na₂Zn₂O₃,^[4] Na₁₀Zn₄O₉.^[5]

Notes and References

1. Glenn O. Mallory, Juan B. Hajdu, (1990), Electroless Plating: Fundamentals and Applications, American Electroplaters and Surface Finishers Society,, William Andrew Inc.,
2. Synthese und Kristallstruktur von Na₂Zn(OH)₄, R. Stahl, R. Niewa, H. Jacobs, Zeitschrift für anorganische und allgemeine Chemie, volume 625, pp. 48 - 50,
3. D. Trinschek, M. Jansen (1996): "Na₂ZnO2, ein neues Natriumzinkat". Zeitschrift für Naturforschung B, volume 51, issue 5, pages 711-714.
4. Eine neue Modifikation von Na₂Zn₂O₃, D. Trinschek, M. Jansen:, Z. Naturforschung 51b, (1996), 917-21
5. Ein neues Oxozinkat mit trigonal-planar koordiniertem Zink, D. Trinschek, M. Jansen: Na₁₀Zn₄O₉, Zeitschrift für anorganische und allgemeine Chemie volume 622 (1996), pp. 245-50