Sodium dithionate
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Sodium dithionate | |
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General | |
Systematic name | Sodium dithionate |
Other names | See text |
Molecular formula | Na2S2O6 |
Molar mass | 174.11 g/mol |
Appearance | Gray-white powder. |
CAS number | [7631-94-9] [1] |
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 | |
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 |
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 sulfur that is oxidized relative to elemental sulfur, but not totally oxidized. Sulfur 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 can be used as a reductant, react to reduce other species and be oxidized to sulfate. Sodium dithionate is sufficiently strong a reductant to reduce iron(III) oxide (rust) to iron(II), the more soluble form of iron. Iron(III) is common in soils and clays and gives clays a reddish hue.
When sodium dithionate acts as a reductant, it undergoes:
2 Na+ + 4 H2O + S2O42- → 2 SO42- + 8 H+ + 6 e- + 2 Na+