physics

Plutonium(III) chloride

Plutonium(III) chloride is a physics 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 Plutonium(III) chloride rather than just read about it. In short: Plutonium(III) chloride or plutonium trichloride is an inorganic compound of plutonium and chlorine with the chemical formula PuCl3. It is the only stable solid chloride of plutonium, though another plutonium chloride, plutonium tetrachloride, is known in the gas phase.

Key takeaways

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

Reference excerpt

Plutonium(III) chloride or plutonium trichloride is an inorganic compound of plutonium and chlorine with the chemical formula PuCl3. It is the only stable solid chloride of plutonium, though another plutonium chloride, plutonium tetrachloride, is known in the gas phase. It can exist as an anhydrous solid (containing no water), or in the form of hydrates (solids containing water), such as the hexahydrate, PuCl3·6H2O. It is used in the processing of plutonium metal and in molten-salt reactors. Plutonium(III) chloride can be synthesized through a variety of reactions, many involving the reaction of other plutonium compounds, such as plutonium(III) oxalate (Pu2(C2O4)3), plutonium(IV) oxide (PuO2), or plutonium hydride (PuHx), with chlorinating agents like hydrogen chloride (HCl), hexachloropropene (C3Cl6), phosgene (COCl2), carbon tetrachloride (CCl4), or chlorine gas (Cl2). The structure of both anhydrous plutonium(III) chloride and PuCl3·6H2O are known.

Synthesis Multiple different methods have been used to synthesize plutonium(III) chloride, which all involve the chlorination of plutonium or plutonium compounds. Many of these methods also use plutonium(III) oxalate, which can be prepared by carefully adding oxalic acid to an acidic plutonium(III) solution, resulting in the decahydrate, Pu2(C2O4)3·10H2O. Purification of PuCl3 is achieved through sublimation, just as in other lanthanide and actinide trihalides.

Using hydrogen chloride For medium-scale reactions (between 1 and 10 grams), the best method of preparing plutonium(III) chloride is by reacting plutonium(III) oxalate with hydrogen chloride, HCl:

Pu2(C2O4)3·10H2O + 6 HCl → 2 PuCl3 + 3 CO2 + 3 CO + 13 H2O For processing 100 gram quantities of plutonium, it can be converted to plutonium hydride which is reacted with hydrogen chloride in a fluidized bed reactor at 450 °C. To remove oxychlorides, the resulting PuCl3 is melted at 800 °C and sparged with HCl for 45 minutes. Plutonium(III) chloride can also be formed from an aqueous solution of hydrogen chloride (hydrochloric acid) containing plutonium(III). Upon evaporation of the HCl solution, a residue of plutonium(III) chloride hexahydrate, PuCl3·6H2O, is formed. The hexahydrate can then be dehydrated in a stream of HCl to give the anhydrous solid PuCl3. Hydrogen chloride corrodes plutonium metal, forming plutonium(III) chloride as a thin surface layer:

2 Pu + 6 HCl → 2 PuCl3 + 3 H2

Using hexachloropropene Due to the difficulty in handling hazardous gases, hexachloropropene (C3Cl6) is used as a chlorinating agent instead of more dangerous compounds. Plutonium(III) oxalate (Pu2(C2O4)3) has been used as an efficient initial source of plutonium. To produce plutonium(III) chloride, Pu2(C2O4)3 is heated with C3Cl6:

Pu2(C2O4)3·10H2O + 3 C3Cl6 → 2 PuCl3 + 3 C3Cl4O + 3 CO2 + 3 CO + 10 H2O

Using chlorine gas Plutonium(III) chloride can be produced via reacting plutonium metal with chlorine gas at temperatures between 300 °C and 500 °C, followed by sublimation at 600–800 °C. Chlorine is used to chlorinate plutonium(IV) oxide (PuO2) in the carbochlorination process, in which carbon is used as a reducing agent:

2 PuO2 + 3 C + 3 Cl2 → 2 PuCl3 + 2 CO + CO2

Using other gaseous chlorinating agents Plutonium(IV) oxide (PuO2) can also be chlorinated with phosgene (COCl2) or carbon tetrachloride above 500 °C, yielding analytically pure samples of PuCl3. This method has been used at Los Alamos National Laboratory. One method for the continuous production of PuCl3 using phosgene is as follows: Plutonium(IV) oxalate hydrate (Pu(C2O4)2·6H2O) is precipitated from plutonium(IV) solution, dried, and calcined (heated to decomposition without oxygen) to form plutonium(IV) oxide (PuO2). The resulting PuO2 is then heated with phosgene in a tube furnace at 500 °C. This method produces plutonium at a rate of 250 grams / hour.

Using ammonium chloride To ensure a high-purity product, plutonium(III) chloride can be prepared by reacting plutonium metal with ammonium chloride at high temperatures. The ammonium chloride sublimes, producing ammonia (NH3) and hydrogen chloride. The hydrogen chloride subsequently reacts with the plutonium metal to form PuCl3:

2 Pu + 6 NH4Cl → 2 PuCl3 + 6 NH3 + 3 H2

Properties The color of plutonium(III) chloride depends on its method of production. Plutonium(III) chloride produced via dehydration of the hexahydrate is slate-blue, while when prepared by one of the anhydrous methods the compound is blue-green to emerald green. When condensated from the gas phase, it appears as an emerald green solid. It is significantly hygroscopic, and is readily hydrated by atmospheric moisture, requiring it to be kept in an controlled, dehumidified atmosphere. Its hydration by atmospheric moisture leads to the formation of several hydrates, or compounds containing water. These include the monohydrate (PuCl3·H2O), dihydrate (PuCl3·2H2O), and hexahydrate (PuCl3·6H2O). Which hydrate is formed depends on the partial pressure of water in the atmosphere. Plutonium(III) chloride hexahydrate has a melting point of 94 °C, at which it melts in its own waters of crystallization, forming a solution. In a vacuum at 27 °C, it decomposes to give the monohydrate, and upon heating between 400 and 520 °C, it gives plutonium oxychloride, PuOCl. It is the only stable solid binary chloride of plutonium, but other chlorides are known in the gas phase. When heated with chlorine at high temperatures, plutonium(III) chloride reacts to form the compound plutonium tetrachloride, increasing its volatility. Upon condensing, it reverts to PuCl3.

2 PuCl3 + Cl2 ⇌ 2 PuCl4 PuCl3 is also antiferromagnetic below temperatures of around 4.5 K.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Plutonium(III) chloride

Start with the simplest possible case. Write down what Plutonium(III) chloride claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, 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 Plutonium(III) chloride 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 Plutonium(III) chloride 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 Plutonium(III) chloride

In research: Plutonium(III) chloride appears in physics 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 Plutonium(III) chloride 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: Plutonium(III) chloride is common in secondary-school and first-year university syllabi. It links to neighbouring topics Actinide halides, Chlorides, Nuclear materials, so understanding it makes those chapters shorter.
In everyday life: Look for Plutonium(III) chloride 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 Plutonium(III) chloride in 20 minutes

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

Frequently asked questions

What is Plutonium(III) chloride in simple terms?

Why does Plutonium(III) chloride matter?

Because it connects several physics 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 Plutonium(III) chloride?

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 Plutonium(III) chloride.