chemistry

Sodium phosphide

Sodium phosphide 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 Sodium phosphide rather than just read about it. In short: Sodium phosphide is the inorganic compound with the formula Na3P. It is a black solid.

Key takeaways

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

Reference excerpt

Sodium phosphide is the inorganic compound with the formula Na3P. It is a black solid. It is often described as Na+ salt of the P3− anion. Na3P is a source of the highly reactive phosphide anion. It should not be confused with sodium phosphate, Na3PO4. In addition to Na3P, five other binary compositions of sodium and phosphorus are known: NaP, Na3P7, Na3P11, NaP7, and NaP15.

Structure and Properties The compound crystallizes in a hexagonal motif, often called the sodium arsenide structure. Like K3P, solid Na3P features pentacoordinate P centers.

Preparation The first preparation of Na3P was first reported in the mid-19th century. French researcher, Alexandre Baudrimont prepared sodium phosphide by treating molten sodium with phosphorus pentachloride.

8 Na(l) + PCl5 → 5 NaCl + Na3P Many different routes to Na3P have been described. Due to its flammability and toxicity, Na3P (and related salts) is often prepared and used in situ. White phosphorus is reduced by sodium-potassium alloy:

P4 + 12 Na → 4 Na3P Phosphorus reacts with sodium in an autoclave at 150 °C for 5 hours to produce Na3P. Alternatively the reaction can be conducted at normal pressures but using a temperatures gradient to generate nonvolatile NaxP phases (x < 3) that then react further with sodium. In some cases, an electron-transfer agent, such as naphthalene, is used. In such applications, the naphthalene forms the soluble sodium naphthalenide, which reduces the phosphorus.

Uses Sodium phosphide is a source of the highly reactive and highly basic phosphide anion. The material is insoluble in all solvents but reacts as a slurry with acids and related electrophiles to give derivatives of the type PM3:

Na3P + 3 E+ → E3P (E = H, Me3Si) The trimethylsilyl derivative is volatile (b.p. 30-35 C @ 0.001 mm Hg) and soluble. It serves as a soluble equivalent to "P3−". Indium phosphide, a semiconductor arises by treating in-situ generated "sodium phosphide" with indium(III) chloride in hot N,N’-dimethylformamide as solvent. In this process, the phosphide reagent is generated from sodium metal and white phosphorus, whereupon it immediately reacts with the indium salt:

Na3P + InCl3 → InP + 3NaCl

Precautions Sodium phosphide is highly dangerous releasing toxic phosphine upon hydrolysis, a process that is so exothermic that fires result. The USDOT has forbidden the transportation of Na3P on aircraft and trains due to the potential fire and toxic hazards.

References

Illustrations

Worked examples

Example 1 — a first encounter with Sodium phosphide

Start with the simplest possible case. Write down what Sodium phosphide 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 Sodium phosphide 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 Sodium phosphide 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 Sodium phosphide

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

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

Frequently asked questions

What is Sodium phosphide in simple terms?

Sodium phosphide is the inorganic compound with the formula Na3P. It is a black solid.

Why does Sodium phosphide 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 Sodium phosphide?

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 Sodium phosphide.