chemistry

Sodium bromide

Sodium bromide 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 bromide rather than just read about it. In short: Sodium bromide is an inorganic compound with the formula NaBr. It is a high-melting white, crystalline solid that resembles sodium chloride.

Key takeaways

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

Reference excerpt

Sodium bromide is an inorganic compound with the formula NaBr. It is a high-melting white, crystalline solid that resembles sodium chloride. It is a widely used source of the bromide ion and has many applications. In repeated doses it is toxic to humans, leading to bromism, which may include symptoms such as skin rashes, drowsiness, nausea, and hallucinations.

Synthesis, structure, reactions NaBr crystallizes in the same cubic motif as NaCl, NaF and NaI. The anhydrous salt crystallizes above 50.7 °C. Dihydrate salt (NaBr·2H2O) crystallize out of water solution below 50.7 °C. NaBr is produced by treating sodium hydroxide with hydrogen bromide. Sodium bromide can be used as a source of the chemical element bromine. This can be accomplished by treating an aqueous solution of NaBr with chlorine gas:

2 NaBr + Cl2 → Br2 + 2 NaCl

Applications Sodium bromide is the most useful inorganic bromide in industry. It is also used as a catalyst in TEMPO-mediated oxidation reactions.

Medicine

Also known as Sedoneural, sodium bromide has been used as a hypnotic, anticonvulsant, and sedative in medicine, widely used as an anticonvulsant and a sedative in the late 19th and early 20th centuries. Its action is due to the bromide ion, and for this reason potassium bromide is equally effective. In 1975, bromides were removed from drugs in the U.S. such as Bromo-Seltzer due to toxicity.

Preparation of other bromine compounds Sodium bromide is widely used for the preparation of other bromides in organic synthesis and other areas. It is a source of the bromide nucleophile to convert alkyl chlorides to more reactive alkyl bromides by the Finkelstein reaction:

NaBr + RCl → RBr + NaCl (R = alkyl) Once a large need in photography, but now shrinking, the photosensitive salt silver bromide is prepared using NaBr.

Disinfectant Sodium bromide is used in conjunction with chlorine as a disinfectant for hot tubs and swimming pools.

Petroleum industry Because of its high solubility in water (943.2 g/L or 9.16 mol/L, at 25 °C) sodium bromide is used to prepare dense drilling fluids used in oil wells to compensate a possible overpressure arising in the fluid column and to counteract the associated trend to blow out. The presence of the sodium cation also causes the bentonite added to the drilling fluid to swell, while the high ionic strength induces bentonite flocculation.

Safety NaBr has a very low toxicity with an oral LD50 estimated at 3.5 g/kg for rats. However, this is a single-dose value. Bromide ions are a cumulative toxin with a relatively long biological half-life (in excess of a week in humans): see potassium bromide. Human consumption can lead to bromism.

References

External links

Information about NaBr. Bromide Poisoning in Angola

Illustrations

Worked examples

Example 1 — a first encounter with Sodium bromide

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

In research: Sodium bromide 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 bromide 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 bromide is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alkali metal bromides, Bromides, GABAA receptor positive allosteric modulators, so understanding it makes those chapters shorter.
In everyday life: Look for Sodium bromide 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 bromide in 20 minutes

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

Frequently asked questions

What is Sodium bromide in simple terms?

Sodium bromide is an inorganic compound with the formula NaBr. It is a high-melting white, crystalline solid that resembles sodium chloride.

Why does Sodium bromide 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 bromide?

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 bromide.