Sodium stannate

 ( Stannates ) 

Sodium stannate, formally sodium hexahydroxostannate(IV), is the inorganic compound with the formula Na₂Sn(OH)₆. This colourless salt forms upon dissolving metallic tin or tin(IV) oxide in sodium hydroxide and is used as a stabiliser for hydrogen peroxide.

In older literature, are sometimes represented as having the simple oxyanion SnO₃²⁻,Similarly, stannites are sometimes represented with the anion SnO₂²⁻ in which case this compound is sometimes named as sodium stannate–3–water and represented as Na₂SnO₃·3H₂O, a hydrate with three waters of crystallisation. The anhydrous form of sodium stannate, Na₂SnO₃, is recognised as a distinct compound with its own CAS Registry Number, and a distinct material safety data sheet.

Alkali metal stannate compounds are prepared by dissolving elemental tin in a suitable metal hydroxide, in the case of sodium stannate by the reaction:

(1997). 9780750633659, Butterworth-Heinemann. ISBN 9780750633659

Sn   +   2 NaOH   +   4 H₂O   →   Na₂Sn(OH)₆   +   2 H₂

A similar reaction occurs when tin dioxide is dissolved in base:

SnO₂   +   2 NaOH   +   2 H₂O   →   Na₂Sn(OH)₆

The anhydrous form can also be prepared from tin dioxide by roasting with sodium carbonate in a mixed carbon monoxide / carbon dioxide environment:

SnO₂   +   Na₂CO₃   →   Na₂SnO₃   +   CO₂

The anion is a coordination complex that is octahedral in shape, similar to most stannates, such as the hexachlorostannate anion . The Sn—O bond distances average 2.071 Å.

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See also

• Sodium carbonate
• Sodium silicate
• Sodium germanate

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