Sodium Sulfite
Basic Information
Name: Sodium Sulfite
Other names: Sodium sulphite; disodium sulfite
Molecular formula: Na2SO3 (anhydrous) / Na2SO3·7H2O (heptahydrate)
Molecular weight: 126.04 (anhydrous) / 252.15 (heptahydrate)
CAS number: 7757-83-7 (anhydrous) / 10102-15-5 (heptahydrate)
2.Physical and Chemical Properties
- Appearance: Anhydrous - white crystalline powder; heptahydrate - colorless crystals
- Density: Anhydrous approximately 2.63 g/cm³
- Solubility: Soluble in water (anhydrous about 28 g/100 mL at 25 °C); slightly soluble in ethanol Reducing property: A strong reducing agent that is readily oxidized to sodium sulfate in air Aqueous solution: Weakly alkaline
- Stability: Anhydrous form is stable; heptahydrate readily loses water and oxidizes in air
3.Main Functions and Applications (What are its uses?)
- Water treatment (core application): An oxygen scavenger for boiler feed water and a dechlorination agent for wastewater treatment.
- Pulp and paper: Used for dechlorination after bleaching.
- Textile and dyeing: Serves as a reducing agent and for dechlorination. Photography: Acts as a preservative in developers to prevent oxidation. Food: Employed as a preservative and antioxidant (E221).
- Chemical industry: Used as a reducing agent and as a raw material for sodium thiosulfate.
- Metallurgy and ore dressing: Applied as a reducing agent and depressant.
4.A Benchmark-Level Industrial Masterpiece - A Meticulously Crafted "Premium-Grade" Reducing Agent!
Na2SO3 content reaches 97.0% or higher, meeting the premium grade and delivering dependable reducing and dechlorination power.
Low water-insoluble matter, chloride, free alkali, iron and heavy metals ensure clean dissolution and consistent performance.
High purity and strong reducing performance make it a trusted choice for boiler water treatment and bleaching processes.
Available in both anhydrous and heptahydrate forms to suit specific process requirements. "What you see is what you get" - every lot ships with a complete certificate of analysis.
Product Specification - Sodium Sulfite
|
Product model |
Sodium Sulfite (Anhydrous / Heptahydrate) |
|
Molecular formula |
Na2SO3 (anhydrous) / Na2SO3·7H2O (heptahydrate) |
|
CAS number |
7757-83-7 (anhydrous) / 10102-15-5 (heptahydrate) |
|
Appearance |
White crystalline powder |
|
Na2SO3 content (%) |
≥ 97.0 |
|
Water-insoluble matter (%) |
≤ 0.03 |
|
Chloride (as NaCl, %) |
≤ 0.10 |
|
Free alkali (as Na2CO3, %) |
≤ 0.40 |
|
Iron (Fe, %) |
≤ 0.005 |
|
Heavy metals (as Pb, %) |
≤ 0.001 |
|
pH (5% aqueous solution) |
8.5 – 10.0 |
|
Packaging |
25 kg / 50 kg woven bag |
- Test methods reference: Na2SO3 content by iodometric titration; water-insoluble matter by gravimetric method (GB/T 9738); chloride by turbidimetric method; free alkali by acid-base titration; iron by spectrophotometric method (GB/T 3049); heavy metals by colorimetric method.
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