General Chemical manufactures three Grades of anhydrous sodium metabisulfite: NF (Drug) and Food, Photographic, and Technical Grades. A 39% solution of sodium bisulfite is also available.

When sodium metabisulfite is dissolved in water, a solution of sodium bisulfite is formed according to the following equation:

Na₂S₂O₅+ H₂O ——> 2 NaHSO₃

For many years, General Chemical has been a reliable source of high quality anhydrous sodium metabisulfite and a 39% Solution of sodium bisulfite.

In its general reactions, sodium metabisulfite (like sulfites and hydrogen sulfites) is a moderately strong reducing agent which yields sulfate upon reaction with oxidizing agents.

In the anhydrous form, reaction with acids also liberates sulfur dioxide. When dissolved in water to form sodium bisulfite, reaction with an acid also liberates sulfur dioxide. Decreasing pH increases the liberation of sulfur dioxide.

Addition compounds are formed with oxides, unsaturated organic compounds, aldehydes and some ketones, as well as naphthoquinones and aminothiazole derivatives. Sodium bisulfite reacts with epoxides, cyclic imines and episulfides, by ring cleavage and formation of the corresponding sulfonate.

Anhydrous sodium metabisulfite is stable in dry air. In the presence of traces of water, it develops an irritating odor of sulfur dioxide, is slowly oxidized to sodium sulfate and will cake. On heating, anhydrous sodium metabisulfite loses sulfur dioxide. At 150 °C the evolution of sulfur dioxide is very rapid resulting in the formation of sodium sulfite and sulfur dioxide.

Parts of 100% of material required to yield one part of sulfur dioxide.

Sodium metabisulfite and sodium bisulfite solution can be readily oxidized and many of their industrial applications are based on their reducing properties. They are also effective dechlorinating agents.

The major industrial applications are listed below:

1. Component in redox catalysts used in polymerization.
2. Treatment of water and waste water:
• Oxygen scavenging
• Dechlorination
• Treatment of chromium waste liquors.
3. Manufacture of surfactants.
4. Photography.
5. Manufacture of cornstarch, high-fructose corn syrup and oxidized starches.
6. Beverage and food uses.
7. Manufacture of flavors, fragrances and medicines.
8. Vegetable tanning.
9. Purification of molybdenite ores.
10. Dye manufacture.
11. Manufacture of textiles and pulp and paper.

Sodium Metabisulfite is shipped in containers developed to meet the specific requirements of the product and of the consuming industries.