chemistry

Hydrobromic acid

Hydrobromic acid 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 Hydrobromic acid rather than just read about it. In short: Hydrobromic acid is an aqueous solution of hydrogen bromide. It is a strong acid formed by dissolving the diatomic molecule hydrogen bromide (HBr) in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C (255.7 °F) and contains 47.6% HBr by mass, which is 8.77 mol/L.

Key takeaways

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

Reference excerpt

Hydrobromic acid is an aqueous solution of hydrogen bromide. It is a strong acid formed by dissolving the diatomic molecule hydrogen bromide (HBr) in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C (255.7 °F) and contains 47.6% HBr by mass, which is 8.77 mol/L. Hydrobromic acid is one of the strongest mineral acids known.

Uses and reactions Hydrobromic acid is mainly used for the production of inorganic bromides such as the hydrated bromides of iron, nickel, and zinc. Hydrobromic acid is a useful reagent for generating organobromine compounds. It converts primary alcohols to alkyl bromides. Certain ethers are cleaved with HBr. HBr participates in anti-Markovnikov hydrohalogenation of alkenes in the presence of peroxides. The resulting 1-bromoalkanes are versatile alkylating agents, giving rise to fatty amines and quaternary ammonium salts. In the presence of hydrogen peroxide, it gives bromine. Since elemental bromine can be dangerous to handle, the H2O2/HBr mixture is used instead, e.g. for aromatic brominations:

2 ArH + 2 HBr + H2O2 → 2 ArBr + 2 H2O (Ar = aryl) Industrially significant organic compounds prepared from hydrobromic acid include allyl bromide, the fire-retardant tetrabromobisphenol A, and bromoacetic acid.

Synthesis Hydrobromic acid can be prepared in the laboratory via the reaction of Br2, SO2, and water.

Br2 + SO2 + 2 H2O → H2SO4 + 2 HBr More typically laboratory preparations involve the production of anhydrous HBr, which is then dissolved in water. Hydrobromic acid has commonly been prepared industrially by reacting bromine with either sulfur or phosphorus and water. However, it can also be produced electrolytically. It can also be prepared by treating bromides with non-oxidising acids like phosphoric or acetic acids. Alternatively the acid can be prepared with dilute (5.8M) sulfuric acid and potassium bromide:

H2SO4 + KBr → KHSO4 + HBr Using more concentrated sulfuric acid or allowing the reaction solution to exceed 75 °C further oxidizes HBr to elemental bromine. The acid is further purified by filtering out the KHSO4 and by distilling off the water until the solution reaches an azeotrope (124.3 °C). The yield is approximately 85%. Hydrobromic acid is available commercially in various concentrations and purities.

References

External links Media related to Hydrogen bromide at Wikimedia Commons

International Chemical Safety Card 0282 NIOSH Pocket Guide to Chemical Hazards Carlin, W. W. U.S. patent 4,147,601

Illustrations

Worked examples

Example 1 — a first encounter with Hydrobromic acid

Start with the simplest possible case. Write down what Hydrobromic acid 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 Hydrobromic acid 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 Hydrobromic acid 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 Hydrobromic acid

In research: Hydrobromic acid 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 Hydrobromic acid 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: Hydrobromic acid is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bromides, Mineral acids, Nonmetal halides, so understanding it makes those chapters shorter.
In everyday life: Look for Hydrobromic acid 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 Hydrobromic acid in 20 minutes

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

Frequently asked questions

What is Hydrobromic acid in simple terms?

Why does Hydrobromic acid 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 Hydrobromic acid?

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 Hydrobromic acid.