Telluric acid

Telluric acid is a chemical compound with the formula Te(OH)_6. It is a white crystalline solid that is soluble in water, producing a mildly acidic solution. Telluric acid is one of the most important tellurium compounds and serves as a precursor to many other tellurium compounds.

Properties

Telluric acid is a hexahydrate of tellurium, and its structure consists of TeO_6 octahedra with each tellurium atom being surrounded by six oxygen atoms. This structure is somewhat similar to that of sulfuric acid, H_2SO_4, and selenic acid, H_2SeO_4, reflecting the position of tellurium in the chalcogen group of the periodic table. However, unlike these acids, telluric acid is less acidic and has weaker oxidizing properties.

Synthesis

Telluric acid can be synthesized by oxidizing tellurium or tellurium dioxide (TeO_2) with nitric acid (HNO_3) or hydrogen peroxide (H_2O_2). The reaction with hydrogen peroxide is particularly efficient and yields telluric acid directly: \[ \text{TeO}_2 + \text{H}_2\text{O}_2 \rightarrow \text{Te(OH)}_6 \]

Applications

While telluric acid itself is not widely used in industrial applications, it is an important starting material for the synthesis of other tellurium compounds. For example, it can be used to prepare tellurates, the salts of telluric acid, by neutralization with bases. These tellurates are used in some electrochemical processes and in the glass industry to impart unique properties to glass, such as improved resistance to acids and alkalis.

Safety

Telluric acid, like many tellurium compounds, is considered to be of low toxicity. However, it should be handled with care to avoid ingestion, inhalation, or skin contact, as it can cause irritation and other adverse health effects. Proper personal protective equipment (PPE) should be used when handling telluric acid or its solutions.

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