chemistry

Rhenium trioxide

Rhenium trioxide 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 Rhenium trioxide rather than just read about it. In short: Rhenium trioxide or rhenium(VI) oxide is an inorganic compound with the formula ReO3. It is a red solid with a metallic lustre that resembles copper in appearance.

Key takeaways

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

Reference excerpt

Rhenium trioxide or rhenium(VI) oxide is an inorganic compound with the formula ReO3. It is a red solid with a metallic lustre that resembles copper in appearance. It is the only stable trioxide of the Group 7 elements (Mn, Tc, Re).

Preparation and structure Rhenium trioxide can be formed by reducing rhenium(VII) oxide with carbon monoxide at 200 °C or elemental rhenium at 400 °C.

Re2O7 + CO → 2 ReO3 + CO2 3 Re2O7 + Re → 7 ReO3 Re2O7 can also be reduced with dioxane.

Rhenium trioxide crystallizes with a primitive cubic unit cell, with a lattice parameter of 3.742 Å (374.2 pm). The structure of ReO3 is similar to that of perovskite (ABO3), without the large A cation at the centre of the unit cell. Each rhenium center is surrounded by an octahedron defined by six oxygen centers. These octahedra share corners to form the 3-dimensional structure. The coordination number of O is 2, because each oxygen atom has 2 neighbouring Re atoms.

Properties

Physical properties ReO3 is unusual for an oxide because it exhibits very low resistivity. It behaves like a metal in that its resistivity decreases as its temperature decreases. At 300 K, its resistivity is 100.0 nΩ·m, whereas at 100 K, this decreases to 6.0 nΩ·m, 17 times less than at 300 K.

Chemical properties Rhenium trioxide is insoluble in water, as well as dilute acids and bases. Heating it in base results in disproportionation to give ReO2 and ReO−4, while reaction with acid at high temperature affords Re2O7. In concentrated nitric acid, it yields perrhenic acid. Upon heating to 400 °C under vacuum, it undergoes disproportionation:

3 ReO3 → Re2O7 + ReO2 Rhenium trioxide can be chlorinated to give rhenium trioxide chloride:

2 ReO3 + Cl2 → 2 ReO3Cl Rhenium trioxide serves as host for the intercalation of one and two equivalents of lithium. Lithium can be incorporated using butyl lithium:

ReO3 + C4H9Li → LiReO3 + 0.5 C8H18 LiReO3 + C4H9Li → Li2ReO3 + 0.5 C8H18 Re remains octahedral before and after intercalation, but the framework distorts.

Uses

Hydrogenation catalyst Rhenium trioxide finds some use in organic synthesis as a catalyst for amide reduction.

References

Illustrations

Worked examples

Example 1 — a first encounter with Rhenium trioxide

Start with the simplest possible case. Write down what Rhenium trioxide 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 Rhenium trioxide 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 Rhenium trioxide 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 Rhenium trioxide

In research: Rhenium trioxide 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 Rhenium trioxide 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: Rhenium trioxide is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hydrogenation catalysts, Rhenium compounds, Transition metal oxides, so understanding it makes those chapters shorter.
In everyday life: Look for Rhenium trioxide 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 Rhenium trioxide in 20 minutes

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

Frequently asked questions

What is Rhenium trioxide in simple terms?

Rhenium trioxide or rhenium(VI) oxide is an inorganic compound with the formula ReO3. It is a red solid with a metallic lustre that resembles copper in appearance.

Why does Rhenium trioxide 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 Rhenium trioxide?

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 Rhenium trioxide.