Sodium bismuthate

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Sodium bismuthate

NaBiO3 powder.
Names
Other names
Sodium bismuth oxide
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.032.220 Edit this at Wikidata
EC Number
  • 235-455-6
UNII
  • InChI=1S/Bi.Na.3O/q;+1;;;-1
  • [O-][Bi](=O)=O.[Na+]
Properties
NaBiO3
Molar mass 279.968 g/mol
Appearance Yellow to yellowish-brown odorless powder[1]
Density 6.50 g/cm3
Insoluble in cold, decomposes in hot water[2]
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H302, H315, H319, H335
P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P403+P233, P405, P501
Lethal dose or concentration (LD, LC):
420 mg/kg (rat, oral)[1]
Related compounds
Other anions
Sodium antimonate
Other cations
 Potassium bismuthate
Related compounds
 Sodium hexafluorobismuthate(V)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Sodium bismuthate is an

hygroscopic,[2] but not soluble in cold water, which can be convenient since the reagent can be easily removed after the reaction. It is one of the few water insoluble sodium salts. Commercial samples may be a mixture of bismuth(V) oxide, sodium carbonate and sodium peroxide.[4]

A related compound with the approximate formula Na3BiO4 also exists.[5]

Structure

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.[6]

Synthesis

Bismuth oxidizes to the +V oxidation state only with difficulty in the absence of alkali. Synthesis is performed by making a suspension of bismuth trioxide in a boiling sodium hydroxide solution. It is then oxidized by addition of bromine to form sodium bismuthate.[7]

Bi2O3 + 6 NaOH + 2 Br2 → 2 NaBiO3 + 4 NaBr + 3 H2O

Another synthesis of NaBiO3 involves oxidizing a mixture of sodium oxide and bismuth(III) oxide with air (as the source of O2):[8]

Na2O + Bi2O3 + O2 → 2 NaBiO3

The procedure is analogous to the oxidation of manganese dioxide in alkali to give sodium manganate.

Vial of NaBiO3

Reactions

Storage conditions with moisture and high temperatures are detrimental to sodium bismuthate, as it oxidizes water, decomposing into sodium hydroxide and bismuth(III) oxide:[2]

2 NaBiO3 + H2O → 2 NaOH + Bi2O3 + O2

It is decomposed faster by

chlorine gas.[2]

NaBiO3 may be used to detect manganese qualitatively and quantitatively. As a strong oxidizer, it converts almost any manganese compound to

spectrophotometrically.[3] To do this, some NaBiO3 and the sample are reacted in a hot solution of sulfuric acid or nitric acid.[2] Permanganate has a violet color and maximum absorbance at 510 nm. The reaction is:[citation needed
]

2 Mn2+ + 5 NaBiO3 + 14 H+ → 2 MnO−
4 + 5 Bi3+ + 5 Na+ + 7 H2O

Sodium bismuthate can perform oxidative 1,2-cleavage on

alpha hydroxy acids with no further oxidation of the (possible) aldehyde products:[9]

R2C(OH)–C(OH)–R2 → R2C=O + O=CR2
R2C(OH)–C(O)–R → R2C=O + RCOOH
R2C(OH)–COOH → R2C=O + CO2

These cleavages can be done in the presence of

Lead tetraacetate performs similar reactions, but anhydrous conditions, as required in the use of lead tetraacetate, are not necessary for sodium bismuthate.[9]

NaBiO3 can be used for lab-scale plutonium separation (see bismuth phosphate process).

Safety

NaBiO3 is a mild mechanical

toxicity of bismuth. Oral absolute lethal dose (LD100) of NaBiO3 is 720 mg/kg for rats, and 510 mg/kg for rabbits.[10]

References

Citations

  1. ^ a b c "Sodium bismuthate". Mallinckrodt Baker. 2007-06-19.
  2. ^
    ISBN 9781584881292
    .
  3. ^
    ISBN 978-0-08-037941-8
    .
  4. ^ Suzuki, pp. 1-20
  5. doi:10.18419/opus-6540
    .
  6. doi:10.1016/S0025-5408(00)00453-0. – via ScienceDirect
     (Subscription may be required or content may be available in libraries.)
  7. OCLC 310719485
    .
  8. ISBN 9780080379418
    .
  9. ^ a b Suzuki, p. 373
  10. ISBN 9789279301223
    . SCCS Number: SCCS/1499/12.
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