chemistry

Lanthanum pentanickel

Lanthanum pentanickel 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 pentanickel rather than just read about it. In short: LaNi5 is a hexagonal intermetallic compound composed of the rare earth element lanthanum and the transition metal nickel. It presents a calcium pentacopper (CaCu5) crystal structure.

Key takeaways

Lanthanum pentanickel 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 pentanickel to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Lanthanum pentanickel from memory before moving on to harder problems.

Reference excerpt

LaNi5 is a hexagonal intermetallic compound composed of the rare earth element lanthanum and the transition metal nickel. It presents a calcium pentacopper (CaCu5) crystal structure. It is a melting compound with the same composition and has hydrogen storage capacity.

Structure LaNi5 has a calcium pentacopper (CaCu5) type crystal structure, with a hexagonal lattice, space group is P6/mmm (No. 191), with lanthanum atom is located at coordinate origin 1a (0,0,0), two nickel atoms are located at 2c (1/ 3,2/3,0) and (2/3,1/3,0), the other three at 3g (1/2,0,1/2), (0,1/2,1/2), (1/2,1/2,1/2), with a=511pm, c=397pm. The unit cell contains 1 LaNi5 atom, the volume is 90×10−24 cm3, the LaNi5 unit cell contains a larger The six deformed tetrahedral voids can be used to fill in hydrogen atoms.

Chemical reactions As a hydrogen storage alloy, LaNi5 can absorb hydrogen to form the hydride LaNi5Hx (x≈6) when the pressure is slightly high and the temperature is low, or when the pressure decreases or the temperature increases, hydrogen can be released to form repeated absorption and release of hydrogen. Energy must be added for the dehydrogenation process to proceed as it is an endothermic reaction. A decrease in temperature will cause the reaction to stop.

Characteristics and applications The hydrogen storage density per unit volume (crystal) of LaNi5H6.5 at 2 bar is equal to the density of gaseous molecular hydrogen at 1800 bar, and all hydrogen can be desorbed at 2 bar. Although the hydrogen storage density in practical applications is reduced due to the aggregation of some LaNi5 powders, it is still higher than the density of liquid hydrogen. This allows safe operation of hydrogen fuel. In order to improve its hydrogen storage performance, metals such as lead or manganese are often used to partially replace nickel. Currently, LaNi5 is commonly used in storage and transportation of hydrogen, hydrogen vehicle power, fuel cells, separation and purification of hydrogen, propylene hydrogenation catalysts, etc.

References

Illustrations

Worked examples

Example 1 — a first encounter with Lanthanum pentanickel

Start with the simplest possible case. Write down what Lanthanum pentanickel 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 pentanickel 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 pentanickel 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 pentanickel

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

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

Frequently asked questions

What is Lanthanum pentanickel in simple terms?

LaNi5 is a hexagonal intermetallic compound composed of the rare earth element lanthanum and the transition metal nickel. It presents a calcium pentacopper (CaCu5) crystal structure.

Why does Lanthanum pentanickel 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 pentanickel?

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 pentanickel.