chemistry

Perxenate

Perxenate 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 Perxenate rather than just read about it. In short: In chemistry, perxenates are salts of the yellow xenon-containing anion XeO4−6. This anion has octahedral molecular geometry, as determined by Raman spectroscopy, having O–Xe–O bond angles varying between 87° and 93°.

Key takeaways

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

Reference excerpt

In chemistry, perxenates are salts of the yellow xenon-containing anion XeO4−6. This anion has octahedral molecular geometry, as determined by Raman spectroscopy, having O–Xe–O bond angles varying between 87° and 93°. The Xe–O bond length was determined by X-ray crystallography to be 1.875 Å.

Synthesis Perxenates are synthesized by the disproportionation of xenon trioxide when dissolved in strong alkali:

2 XeO3 (s) + 4 OH− (aq) → Xe (g) + XeO4−6 (aq) + O2 (g) + 2 H2O (l) When Ba(OH)2 is used as the alkali, barium perxenate can be crystallized from the resulting solution.

Perxenic acid

Perxenic acid is the unstable conjugate acid of the perxenate anion, formed by the solution of xenon tetroxide in water. It has not been isolated as a free acid, because under acidic conditions it rapidly decomposes into xenon trioxide, water, and oxygen gas:

2 HXeO3−6 + 6 H+ → 2 XeO3 + 4 H2O + O2 Its extrapolated formula, H4XeO6, is inferred from the octahedral geometry of the perxenate ion (XeO4−6) in its alkali metal salts. The pKa of aqueous perxenic acid has been indirectly calculated to be below 0, making it an extremely strong acid. Its first ionization yields the anion H3XeO−6, which has a pKa value of 4.29, still relatively acidic. The twice deprotonated species H2XeO2−6 has a pKa value of 10.81. Due to its rapid decomposition under acidic conditions as described above, however, it is most commonly known as perxenate salts, bearing the anion XeO4−6.

Properties Perxenic acid and the anion XeO4−6 are both strong oxidizing agents, capable of oxidising silver(I), copper (II) and manganese(II) to (respectively) silver(III), copper(III), and permanganate. The perxenate anion is unstable in acidic solutions, being almost instantaneously reduced to HXeO−4. The sodium, potassium, and barium salts are soluble. Barium perxenate solution is used as the starting material for the synthesis of xenon tetroxide (XeO4) by mixing it with concentrated sulfuric acid:

Ba2XeO6 (s) + 2 H2SO4 (l) → XeO4 (g) + 2 BaSO4 (s) + 2 H2O (l) Most metal perxenates are stable, except silver perxenate, which decomposes violently.

Applications Sodium perxenate, Na4XeO6, can be used for the analytic separation of trace amounts of americium from curium. The separation involves the oxidation of Am3+ to Am4+ by sodium perxenate in acidic solution in the presence of La3+, followed by treatment with calcium fluoride, which forms insoluble fluorides with Cm3+ and La3+, but retains Am4+ and Pu4+ in solution as soluble fluorides.

References

Worked examples

Example 1 — a first encounter with Perxenate

Start with the simplest possible case. Write down what Perxenate 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 Perxenate 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 Perxenate 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 Perxenate

In research: Perxenate 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 Perxenate 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: Perxenate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Octahedral compounds, Oxyanions, Salts, so understanding it makes those chapters shorter.
In everyday life: Look for Perxenate 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 Perxenate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Perxenate 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 Perxenate out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Perxenate in simple terms?

Why does Perxenate 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 Perxenate?

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 Perxenate.