chemistry

Lanthanum(III) sulfide

Lanthanum(III) sulfide 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 Lanthanum(III) sulfide rather than just read about it. In short: Lanthanum(III) sulfide is a binary inorganic chemical compound of lanthanum metal and sulfur with the chemical formula La2S3. At least three polymorphs are known, referred to as α, β, and γ.

Key takeaways

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

Reference excerpt

Lanthanum(III) sulfide is a binary inorganic chemical compound of lanthanum metal and sulfur with the chemical formula La2S3. At least three polymorphs are known, referred to as α, β, and γ.

Synthesis Lanthanum(III) sulfide can directly be produced by treating metallic lanthanum with sulfur:

2La + 3S → La2S3 Once prepared, lanthanum(III) sulfide can be purified by chemical vapor transport using iodine. Lanthanum(III) sulfide can also be prepared by treating the sulfate with hydrogen sulfide at elevated temperatures:

La2(SO4)3 + 12 H2S → La2S3 + 12 H2O + 12 S

Physical properties Dilanthanum trisulfide forms reddish-yellow crystals of the cubic system, with space group I43d, and unit cell parameters a = 0.8706 nm. The α polymorph features two types of La3+ centers, one with Capped trigonal prismatic molecular geometry and one is bicapped trigonal prismatic molecular geometry. It does not dissolve in cold water.

Chemical properties Reacts with hot water: La2S3 + 6 H2O → 2 La(OH)3 + 3 HS Reacts with acids: La2S3 + 3 HCl → 2 LaCl3 + 3 H2S Oxidized by oxygen in atmosphere: 2 La2S3 + 9 O2 → 2 La2O3 + 6 SO2

Uses La2S3 is used as a precursor to prepare complex compounds. It is also used in glass manufacturing and in optical fibers.

References

Illustrations

Worked examples

Example 1 — a first encounter with Lanthanum(III) sulfide

Start with the simplest possible case. Write down what Lanthanum(III) sulfide 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 Lanthanum(III) sulfide 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 Lanthanum(III) sulfide 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 Lanthanum(III) sulfide

In research: Lanthanum(III) sulfide 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 Lanthanum(III) sulfide 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: Lanthanum(III) sulfide is common in secondary-school and first-year university syllabi. It links to neighbouring topics Lanthanum compounds, Sesquisulfides, so understanding it makes those chapters shorter.
In everyday life: Look for Lanthanum(III) sulfide 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 Lanthanum(III) sulfide in 20 minutes

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

Frequently asked questions

What is Lanthanum(III) sulfide in simple terms?

Lanthanum(III) sulfide is a binary inorganic chemical compound of lanthanum metal and sulfur with the chemical formula La2S3. At least three polymorphs are known, referred to as α, β, and γ.

Why does Lanthanum(III) sulfide 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 Lanthanum(III) sulfide?

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 Lanthanum(III) sulfide.