Sodium bismuth oxide
3D model (JSmol)
|Molar mass||279.97 g/mol|
|Appearance||Light brown powder|
|insoluble in cold, decomposes in hot water|
|R-phrases (outdated)||R22, R36/37/38|
|S-phrases (outdated)||S26, S36|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|420 mg/kg (rat)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Sodium bismuthate is the inorganic compound with the formula NaBiO3. It is a yellowish solid that is a strong oxidiser. It is not soluble in cold water, which is sometimes convenient since the reagent can be easily removed after the reaction. It is one of the few sodium salts that is insoluble in water. It is commercially available however commercial samples may be a mixture of bismuth(V) oxide, sodium carbonate and sodium peroxide. A related compound with the approximate formula Na3BiO4 also exists.
Sodium bismuthate adopts an ilmenite structure, consisting of octahedral bismuth(V) centers and sodium cations. The average Bi-O distance is 2.116 Å. The ilmenite structure is related to the corundum structure (Al2O3) with a layer structure formed by close packed oxygen atoms with the two different cations alternating in octahedral sites.
Synthesis and reactions
Bismuth oxidizes to the +V oxidation state only with difficulty – the simple oxide Bi2O5 remains poorly characterized – and in the absence of alkali. The preparation of this salt involves oxidizing a mixture of Bi2O3 and Na2O with air (as the source of O2):
- Na2O + O2 + Bi2O3 → 2 NaBiO3
Sodium bismuthate oxidizes water, decomposing into bismuth(III) oxide and sodium hydroxide:
- 2 NaBiO3 + H2O → 2 NaOH + Bi2O3 + O2
It is decomposed more rapidly by acids.
As a strong oxidizer, sodium bismuthate converts virtually any manganese compound to permanganate, which is easily assayed spectrophotometrically. It is also used for lab-scale separation of plutonium.
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