Sodium dithionate
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| Sodium dithionate | |
|---|---|
 |
|
| General | |
| Systematic name | Sodium dithionate |
| Other names | See text |
| Molecular formula | Na2S2O6 |
| Molar mass | 174.11 g/mol |
| Appearance | Gray-white powder. |
| CAS number | [] |
| Properties | |
| Density and phase | ? g/cm3, solid. |
| Solubility in water | ? g/100 ml (?°C) |
| Melting point | 52°C (325.15 K) (decomp.) |
| Boiling point | Decomposes. |
| Structure | |
| Molecular shape | ? |
| Coordination geometry |
? |
| Crystal structure | ? |
| Dipole moment | ? D |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | ? |
| NFPA 704 |
3
2
2
|
| Flash point | Non-flammable |
| R/S statement | R: R7, R22, R31. S: S7/8, S26, S28, S43. |
| RTECS number | JP2100000 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Other anions | ? |
| Other cations | ? |
| Related compounds | ? |
| Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references |
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For the sterilizing agent, see sodium metabisulfite
Sodium dithionate Na2S2O6 is an important compound for inorganic chemistry. It is also known under names disodium dithionate, sodium hyposulfate, and sodium metabisulfate.
Can be produced by following reactions:
2 NaHSO3 + MnO2 → Na2S2O6 + Mn(OH)2
3 Cl2 + Na2S2O3·5H2O + 6 NaOH → Na2S2O6 + 6 NaCl + 8 H2O
The dithionate ion represents sulphur that is oxidized relative to elemental sulfur, but not totally oxidized. Sulphur can be reduced to sulfide or totally oxidized to sulfate, with numerous intermediate oxidation states in inorganic moieties, as well as organosulfur compounds. Example inorganic ions include sulfite and thiosulfate.
Sodium dithionate is a very stable compound which is not oxidized by permanganate, dichromate or bromine. It can be be oxidized to sulfate under strongly oxidizing conditions: these include boiling for one hour with 5 M sulfuric acid with an excess of potassium dichromate, or treating with an excess of hydrogen peroxide then boiling with concentrated hydrochloric acid. The Gibbs free energy change for the oxidation is about -300 kJ/mol.
It should not be confused with sodium dithionITE, Na2S2O4, which is a very different compound, and is a powerful reducing agent with many uses in chemistry and biochemistry. Confusion between dithionate and dithionite is commonly encountered, even in manufacturers' catalogues!
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