Sodium sulfite


Sodium Metabisulfite or Sodium Pyrosulfite Used in the IUPAC Naming System. Oh you. Sodium is called metabisulfite, an inorganic compound of the Na2S2O5 chemical formula. This substance is sometimes referred to as "di-sodium" (metabisulfite). This compound is often used as an antiseptic, antioxidant and preservative.

Sodium Metabisulfite is a crystallized powdered sulfur dioxide with a density of 1 to 1.2 kg / l and decomposes at a temperature above 120 ° C. If the compartment in which it is dissolved is completely insoluble, it quickly combines with oxidizing air humidity. The amount of water absorbed by the product in the compartment depends on the degree of penetration, which in turn depends on the relative humidity and temperature. In the case of incorrect storage, it is possible to form hard seeds in the product. All sorts of sodium metabisulfite are easily dissolved in water. In aqueous solutions, it is sodium sulfite.


Sodium Metabis sulfite can be prepared from the evaporation of sulfur dioxide saturated sulfur dioxide solution:

2 HSO3- ⇌ H2O + S2O52-

Which ultimately remains solid Na2S2O5.

Chemical structure

Anion is a combination of Dionites (S2O42-) and Ditonate (S2O62-). Is. Anion contains a SO2 group that is associated with a SO3-bonded group with a negative charge located on the SO3-side. The length of the S-S bond is about 2.22 Å and the S-O bond of "Tunity" and "Tunate" has a length of 1.46 and 1.50 Å.

chemical properties

Sodium Metabisulfite, in combination with water, absorbs the oxygen in the water and releases sulfur dioxide (SO2), which creates an unpleasant smell and makes breathing difficult. The release of sulfur dioxide has converted sodium metabisulfite into a potent reducing agent, and should not be siphoned in rivers and lakes as it seriously impairs the lives of animals and plants. For this reason, the use of sodium metabisulphite has declined dramatically, and carriers such as hydrogen peroxide, with the same effect and odorless, are used to sterilize the equipment.

Sodium Metabisulfite, in combination with acids, releases sulfur dioxide:

Na2S2O5 + 2 HCl → 2 NaCl + H2O + 2 SO2

At high temperatures, it also releases sulfur dioxide and provides sodium sulfite:

Na2S2O5 → Na2SO3 + SO2


- Used as a preservative and antioxidant in food and also known as E223.

- (In people who are allergic to sulfites, they may cause allergic reactions, including respiratory reactions in people with asthma, anaphylaxis, and other allergic reactions.)

- Sodium Metabisulphite and Potassium Metabisulfite is one of the ingredients in Campden Pills used in making wine and beer.

- The acceptable daily intake per kg body weight is 0.7 mg. Sodium metabisulfite has no side effects and is converted into harmless sulfate in the liver by oxidation and is excreted in the urine.

- In the chemical and pharmaceutical industries for various purposes, such as a reducing agent in the purification and separation of aldehydes and ketones, to remove the waste containing bromine from the preparation of color is used.

- To remove excess chlorine in drinking water

- To clean reverse osmosis membranes of drinking water in desalinating systems

- To clean equipment at the brewery

- In certain cases to remove oxygen from water supply water boilers

- For wastewater treatment, for example, plating plants to neutralize chromic acid to remove excess chlorine in the neutralization of cyanides

- To clean and whiten wool, jute and other vegetable fibers

- Dyeing fabrics and printing for the preparation of indigo fats and dissolving other colors

- To dissolve tanning extracts

- In making paper to whitewash wood pulp

- In the photography and film industries to prepare solvents suitable for acid stabilization baths

- Added to local anesthetics (lidocaine, etc.) to prevent oxidation of the adrenalin of the vasoconstrictor contained in them and thereby increase the soluble life

- Used as an excipient in some pills, such as paracetamol. Approximately 0.5 mg is used in epinephrine autoinjectors such as EpiPen.

- Gold is also used for gold deposits (gold soluble in Soltani soluble).

- Used as a bleaching agent in the production of coconut cream

- Used as a source of SO2 (mixed with air or oxygen) to cyanide destruction in commercial gold cyanide processes.

One of the most important aspects related to the health of this substance is that it can be added to blood lameness in a test for diagnosis of sickle cell anemia (or any other similar disease in hemoglobin deformation). The material eliminates sickle cell (during a complex polymerization), and therefore the presence or absence of disease is confirmed.


Biological effects:

All samples of sodium metabisulfite contain a small amount of SO2 that stimulates the eyes and the respiratory system. In contact with acids, hazardous quantities of SO2 may be produced.

In water samples, sodium bisulfite causes severe oxygen depletion and may damage aquatic organisms.

safety tips :

- Sodium Metabisulfite is not included as part of the hazardous substance component. According to our available data, sodium metabisulphite products should be labeled with the label Xn and the letters R, S as follows:

R41: Risk of serious damage to the eyes

R37: Stimulate

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