Arsenic Acid Formula

Arsenic acid is a chemical compound with the formula H3AsO4. It is an inorganic acid and is composed of hydrogen (H), arsenic (As), and oxygen (O) atoms.

The molecule of arsenic acid consists of one central arsenic atom that is covalently bonded to four oxygen atoms, which are arranged in a tetrahedral geometry around the arsenic atom. Each oxygen atom is also bonded to a hydrogen atom, resulting in the formation of four O-H bonds.

The arsenic atom in arsenic acid has five valence electrons, meaning that it can form up to five covalent bonds. In arsenic acid, four of these valence electrons are used to form covalent bonds with the oxygen atoms, while the fifth valence electron is used to form a coordinate covalent bond with a water molecule, which donates its lone pair of electrons to form an As-O(H2O) bond.

Arsenic acid is a weak acid, meaning that it only partially dissociates in aqueous solution to release hydrogen ions (H+). The equilibrium reaction for the dissociation of arsenic acid can be represented as follows:

H3AsO4 + H2O ⇌ H3O+ + H2AsO4-

In this reaction, one hydrogen ion is released from the arsenic acid molecule, producing the hydronium ion (H3O+), and leaving behind the hydrogen arsenate ion (H2AsO4-). This process can occur multiple times, releasing more H+ ions each time, leading to the formation of the dihydrogen arsenate ion (HAsO42-) and finally the hydrogen arsenate ion (AsO43-).

Arsenic acid is a toxic substance and exposure to it can cause harm to human health. Therefore, it should be handled with care and appropriate safety measures should be taken while working with it.