Bisulfitti

Bisulfitti are anions with the chemical formula HSO3-. They are formed when sulfur dioxide dissolves in water, leading to the formation of sulfurous acid, H2SO3. This acid can then lose a proton to form the bisulfite ion. Bisulfite ions exist in equilibrium with sulfite ions (SO32-) and sulfurous acid in aqueous solutions, depending on the pH.

Bisulfites are commonly encountered as salts, such as sodium bisulfite (NaHSO3) or potassium bisulfite (KHSO3). These salts are often used as reducing agents and as preservatives. In the food industry, bisulfites are added to dried fruits, wines, and other products to prevent oxidation and inhibit the growth of microorganisms. This is why labels on some food products may carry warnings about sulfite sensitivity.

The reducing properties of bisulfites are utilized in various chemical processes. They can be used to remove chlorine from water or to decolorize certain substances. In photography, they have been employed as a stop bath to halt the action of developer.

However, bisulfites can also be problematic. For individuals with sulfite sensitivity or asthma, exposure to sulfites can trigger adverse reactions, including respiratory problems. This sensitivity is the reason for the labeling requirements on food and beverage products containing sulfites. In industrial settings, sulfur dioxide, the precursor to bisulfites, is a significant air pollutant.