Selenic acid

Selenic acid

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Chemical formula	CHNO
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Selenic acid is a chemical compound with the formula H₂SeO₄. It is a colorless, hygroscopic liquid that is highly soluble in water. Selenic acid is a strong acid and a powerful oxidizing agent, similar to sulfuric acid.

Structure and Properties

Selenic acid is structurally analogous to sulfuric acid, with selenium replacing sulfur. The molecule consists of a central selenium atom surrounded by four oxygen atoms in a tetrahedral arrangement. Two of these oxygen atoms are bonded to hydrogen, forming hydroxyl groups, while the other two are double-bonded to selenium.

Selenic acid is a strong acid, fully dissociating in aqueous solution to form hydrogen ions (H⁺) and selenate ions (SeO₄²⁻). It is also a potent oxidizing agent, capable of oxidizing many metals and non-metals.

Preparation

Selenic acid can be prepared by the oxidation of selenium dioxide (SeO₂) with hydrogen peroxide (H₂O₂):

SeO₂ + H₂O₂ → H₂SeO₄

Alternatively, it can be produced by the oxidation of selenous acid (H₂SeO₃) using strong oxidizing agents such as potassium permanganate (KMnO₄) or chlorine (Cl₂).

Reactions

Selenic acid is a strong oxidizing agent and can oxidize many substances, including:

• Hydrochloric acid (HCl) to chlorine gas (Cl₂)
• Sulfur dioxide (SO₂) to sulfuric acid (H₂SO₄)
• Iodine (I₂) to iodate (IO₃⁻)

Selenic acid can also react with bases to form selenate salts, such as sodium selenate (Na₂SeO₄) and potassium selenate (K₂SeO₄).

Uses

Selenic acid is used in the synthesis of selenate salts, which are used in various industrial and laboratory applications. It is also used as an oxidizing agent in chemical reactions.

Safety and Handling

Selenic acid is highly corrosive and can cause severe burns upon contact with skin or eyes. It should be handled with appropriate personal protective equipment, including gloves and eye protection. Inhalation of vapors should be avoided, and work with selenic acid should be conducted in a well-ventilated area or fume hood.

Also see

• Sulfuric acid
• Selenous acid
• Selenium dioxide
• Selenate