- Sodium sulfite
Identifiers CAS number PubChem ChemSpider UNII RTECS number WE2150000 Jmol-3D images Image 1 Properties Molecular formula Na2SO3 Molar mass 126.043 g/mol Appearance white solid Density 2.633 g/cm3 (anhydrous)
1.561 g/cm3 (heptahydrate)
33.4 °C (dehydration of heptahydrate)
500 °C (anhydrous)
Solubility in water 678 g/L (18 °C, heptahydrate) Structure Crystal structure hexagonal (anhydrous)
Hazards MSDS ICSC 1200 EU Index Not listed NFPA 704 Flash point Non-flammable Related compounds Other anions Sodium selenite Other cations Potassium sulfite Related compounds Sodium bisulfite
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Sodium sulfite (sodium sulphite) is a soluble sodium salt of sulfurous acid. It is a product of sulfur dioxide scrubbing, a part of the flue gas desulfurization process. It is also used as a preservative to prevent dried fruit from discoloring, and for preserving meats, and is used in the same way as sodium thiosulfate to convert elemental halogens to their respective hydrohalic acids, in photography and for reducing chlorine levels in pools.
- Na2CO3 + H2SO3 → Na2SO3 + CO2 + H2O
The second way of prepare it in lab is reacting sodium hydroxide solution with sulfur dioxide gas:
By adding few drops of concentrated hydrochloric acid it can be tested that sodium sulfite is formed or not. if the solution of Na2SO3 gives bubbles of sulfur dioxide gas with HCl, that means the solution of sodium hydroxide is turned to sodium sulfite:
- Na2SO3 + 2 HCl → 2 NaCl + SO2 + H2O
Sodium sulfite is primarily used in the pulp and paper industry. It is used in water treatment as an oxygen scavenger agent, in the photographic industry to protect developer solutions from oxidation and (as hypo clear solution) to wash fixer (sodium thiosulfate) from film and photo-paper emulsions, in the textile industry as a bleaching, desulfurizing and dechlorinating agent and in the leather trade for the sulfitization of tanning extracts. It is used in the purification of TNT for military use. It is used in chemical manufacturing as a sulfonation and sulfomethylation agent. It is used in the production of sodium thiosulfate. It is used in other applications, including froth flotation of ores, oil recovery, food preservatives, making dyes.
Sodium sulfite is decomposed by even weak acids, giving up sulfur dioxide gas.
- Na2SO3 + 2 H+ → 2 Na+ + H2O + SO2
A saturated aqueous solution has pH of ~9. Solutions exposed to air are eventually oxidized to sodium sulfate. If sodium sulfite is allowed to crystallize from aqueous solution at room temperature or below, it does so as a heptahydrate. The heptahydrate crystals effloresce in warm dry air. Heptahydrate crystals also oxidize in air to form the sulfate. The anhydrous form is much more stable against oxidation by air.
- ^ Merck Index of Chemicals and Drugs, 9th ed. monograph 8451
NaAlO2 · NaBH3(CN) · NaBH4 · NaBr · NaBrO3 · NaCH3COO · NaCN · NaC6H5CO2 · NaC6H4(OH)CO2 · NaCl · NaClO · NaClO2 · NaClO3 · NaClO4 · NaF · NaH · NaHCO3 · NaHSO3 · NaHSO4 · NaI · NaIO3 · NaIO4 · NaMnO4 · NaNH2 · NaNO2 · NaNO3 · NaN3 · NaOH · NaO2 · NaPO2H2 · NaReO4 · NaSCN · NaSH · NaTcO4 · NaVO3 · Na2CO3 · Na2C2O4 · Na2CrO4 · Na2Cr2O7 · Na2MnO4 · Na2MoO4 · Na2O · Na2O2 · Na2O(UO3)2 · Na2S · Na2SO3 · Na2SO4 · Na2S2O3 · Na2S2O4 · Na2S2O5 · Na2S2O6 · Na2S2O7 · Na2S2O8 · Na2Se · Na2SeO3 · Na2SeO4 · Na2SiO3 · Na2Te · Na2TeO3 · Na2Ti3O7 · Na2U2O7 · NaWO4 · Na2Zn(OH)4 · Na3N · Na3P · Na3VO4 · Na4Fe(CN)6 · Na5P3O10 · NaBiO3
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Look at other dictionaries:
sodium sulfite — natrio sulfitas statusas T sritis chemija formulė Na₂SO₃ atitikmenys: angl. sodium sulfite; sulfite rus. натрий сернистокислый; натрия сульфит; сульфит ryšiai: sinonimas – dinatrio trioksosulfatas … Chemijos terminų aiškinamasis žodynas
sodium sulfite — noun : a sulfite of sodium: as a. : the crystalline normal salt Na2SO3 used chiefly as a reducing agent, bleaching agent, and antichlor, in photographic developing and fixing baths, and in preserving foods b. : sodium bisulfite a c … Useful english dictionary
sodium sulfite — noun the sodium salt of sulfurous acid, NaSO, used as a food preservative, in photography and in many industrial applications … Wiktionary
sodium sulfite — Chem. a white, crystalline, water soluble solid, Na2SO3, used chiefly as a food preservative, as a bleaching agent, and as a developer in photography. * * * … Universalium
sodium sulfite — Na2SO3, fairly stable in the anhydrous form; used as a reagent and as a preservative and antioxidant … Medical dictionary
sodium sulfite — A chemical used in photography, paper making, water treatment, and for other purposes … English dictionary of cancer terms
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