H2SO3 , Sulfurous Acid


Sulfurous acid (also salicylic acid) is the chemical compound with the formula H2SO3. There is no evidence that sulfurous acid is present in solution , but the molecule has been detected in the gas phase. However, the conjugate bases of this pseudo-acid contain the common anion, bisulfite (or hydrogen sulfite) and sulfite. Sulfurous acid is an intermediate species in the formation of acid rain from sulfur dioxide.
Raman spectra of a solution of sulfur dioxide in water show only signals due to the SO molecule and the bisulfite ion, HSO. The signal intensity corresponds to the following equilibrium:

Chemical formula H2SO3 . It is known only as an aqueous solution and cannot be removed as a free acid. It is obtained by passing sulfur dioxide SO 2 gas (sulfurous acid gas) through water when water is cooled or ice is cooled . The JIS states that a commercially available reagent, sulfurous acid solution, has an SO 2 content of 6.0% or more . It is a colorless and transparent aqueous solution with an irritating odor. It shows acidity. Dibasic acid, acid dissociation index P K 1 = 1.76, P K 2 = 7.19 (25 °C). SO 2 of 23.7% (weight) or more In an aqueous solution with the material, it separates into two liquid phases at 12.1 °C or higher. It is a strong reducing agent and is oxidized by halogens, hydrogen peroxide , etc. to become sulfuric acid H2SO4.

H2SO3 + H 2 O⇄SO 4 2 ⁺ + 4H 2 + 2e

It also acts as an oxidant and has strong oxidizing power when added to inorganic acids.

4FCl 2 + 4HCl + H2SO3 F → 4FeCl 3 + S + 3H 2 O

When ultraviolet rays are applied for a long time or when heated to a high temperature of 140 ° C or more, the following decomposition occurs.

3 H2SO3 → 2H2SO4 + S + H 2 O

Sulfur dioxide released into the atmosphere dissolves in water covering the surface of suspended particles and turns into sulfurous acid, which is converted to sulfuric acid by a photochromic reaction , which causes the generation of <sulfuric acid mist – which causes significant air pollution . , It is also the cause of acid rain which dissolves in rain and turns into sulfurous acid. Sulfites are generally colorless (for example, Na 2 SO 3 7H 2 O), aqueous solutions are reducible, and are readily oxidized to sulfate in humidified air. alkali metal ortho and hydrogen salts, such as Na 2 SO 3 , NaHSO 3 , K2 SO 3 , KHSO 3 , (NH 4 ) 2 SO 3 , are widely used as reducing agents and are making industrially important and photographic developments as a bleaching agent . Agent for drugs, foods, fiber, etc.

The chemical formula is H2SO3 . It is known simply as aqueous solution and is obtained by immersing sulfur dioxide SO 2 in water. If you heat with a colorless weak acid or add a strong acid (such as sulfuric acid), SO 2 is produced. It is a strong reducing agent and is oxidized to sulfuric acid. It also shows an oxidizing action and it decomposes itself into sulfur.