tetrahydroxystannic

Tetrahydroxystannic acid is an inorganic compound with the chemical formula H2Sn(OH)6. It is also known as stannic acid or hexahydroxystannate. This acid is a weak acid and is the most common form of tin in aqueous solution under alkaline conditions. It exists as a white, gelatinous precipitate when formed by the addition of a base to a soluble tin(IV) salt.

The compound is generally prepared by reacting tin(IV) chloride with a strong base, such as sodium hydroxide or potassium hydroxide. The reaction produces the tetrahydroxystannate anion, Sn(OH)6^2-, which can then be protonated to form the acid. It is important to note that tetrahydroxystannic acid is not typically isolated in its pure, anhydrous form due to its tendency to dehydrate and form tin(IV) oxide.

In solution, tetrahydroxystannic acid is in equilibrium with other tin-containing species, depending on the pH. Under acidic conditions, tin(IV) exists primarily as the Sn^4+ ion or complex aquo species. As the pH increases, hydroxide ions coordinate to the tin ion, leading to the formation of tetrahydroxystannic acid. This acid can react with bases to form stannate salts, such as sodium stannate. Its properties and reactivity are characteristic of a moderately strong Lewis acid.