chemistry

Sodium bismuthate

Sodium bismuthate is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Sodium bismuthate rather than just read about it. In short: Sodium bismuthate is an inorganic compound, and a strong oxidiser with chemical formula NaBiO3. It is somewhat hygroscopic, but not soluble in cold water, which can be convenient since the reagent can be easily removed after the reaction.

Key takeaways

Sodium bismuthate belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Sodium bismuthate to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sodium bismuthate from memory before moving on to harder problems.

Reference excerpt

Sodium bismuthate is an inorganic compound, and a strong oxidiser with chemical formula NaBiO3. It is somewhat hygroscopic, 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. A related compound with the approximate formula Na3BiO4 also exists.

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.

Synthesis Bismuth oxidizes to the +5 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.

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):

Na2O + Bi2O3 + O2 → 2 NaBiO3 The procedure is analogous to the oxidation of manganese dioxide in alkali to give sodium manganate.

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 NaBiO3 + H2O → 2 NaOH + Bi2O3 + O2 It is decomposed faster by acids. In HCl, NaBiO3 also reacts to form chlorine gas.

NaBiO3 may be used to detect manganese qualitatively and quantitatively. As a strong oxidizer, it converts almost any manganese compound to permanganate, which is easily assayed spectrophotometrically. To do this, some NaBiO3 and the sample are reacted in a hot solution of sulfuric acid or nitric acid. Permanganate has a violet color and maximum absorbance at 510 nm. The reaction is:

2 Mn2+ + 5 NaBiO3 + 14 H+ → 2 MnO4− + 5 Bi3+ + 5 Na+ + 7 H2O Sodium bismuthate can perform oxidative 1,2-cleavage on glycols, ketols and alpha hydroxy acids with no further oxidation of the (possible) aldehyde products:

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 acetic or phosphoric acid at room temperature. Alcohols like methanol or ethanol can be used as the reaction media, as they are oxidized slowly with sodium bismuthate. Lead tetraacetate performs similar reactions, but anhydrous conditions, as required in the use of lead tetraacetate, are not necessary for sodium bismuthate. NaBiO3 can be used for lab-scale plutonium separation (see bismuth phosphate process).

Safety NaBiO3 is a mild mechanical irritant. Upon ingestion it is moderately toxic with symptoms akin to lead poisoning: abdominal pain and vomiting. Large doses cause diarrhea and death. Continued absorption of NaBiO3 into body causes permanent kidney damage. These effects are due to the toxicity of bismuth. Oral absolute lethal dose (LD100) of NaBiO3 is 720 mg/kg for rats, and 510 mg/kg for rabbits.

References

Illustrations

Worked examples

Example 1 — a first encounter with Sodium bismuthate

Start with the simplest possible case. Write down what Sodium bismuthate claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sodium bismuthate before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sodium bismuthate ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sodium bismuthate

In research: Sodium bismuthate appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Sodium bismuthate in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Sodium bismuthate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bismuth compounds, Oxygen compounds, Sodium compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Sodium bismuthate outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Sodium bismuthate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Sodium bismuthate means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Sodium bismuthate out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sodium bismuthate in simple terms?

Why does Sodium bismuthate matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sodium bismuthate?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sodium bismuthate.