chemistry

Zinc bromide

Zinc 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 Zinc bromide rather than just read about it. In short: Zinc bromide (ZnBr2) is an inorganic compound with the chemical formula ZnBr2. It is a colourless salt that shares many properties with zinc chloride (ZnCl2), namely a high solubility in water forming acidic solutions, and good solubility in organic solvents.

Key takeaways

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

Reference excerpt

Zinc bromide (ZnBr2) is an inorganic compound with the chemical formula ZnBr2. It is a colourless salt that shares many properties with zinc chloride (ZnCl2), namely a high solubility in water forming acidic solutions, and good solubility in organic solvents. It is hygroscopic and forms a dihydrate ZnBr2·2H2O.

Production ZnBr2 · 2H2O is prepared by treating zinc oxide or zinc metal with hydrobromic acid.

ZnO + 2 HBr + H2O → ZnBr2·2H2O Zn + 2 HBr → ZnBr2 + H2 The anhydrous material can be produced by dehydration of the dihydrate with hot CO2 or by reaction of zinc metal and bromine. Sublimation in a stream of hydrogen bromide also gives the anhydrous derivative.

Structure ZnBr2 crystallizes in the same structure as ZnI2: four tetrahedral Zn centers share three vertices to form “super-tetrahedra” of nominal composition {Zn4Br10}2−, which are linked by their vertices to form a three-dimensional structure. The dihydrate ZnBr2 · 2H2O can be described as ([Zn(H2O)6]2+)2([Zn2Br6]2-). Gaseous ZnBr2 is linear in accordance with VSEPR theory with a Zn–Br bond length of 221 pm.

Uses Zinc bromide is mainly used in servicing oil and natural gas wells, solutions of zinc bromide are used to displace drilling mud when switching from the drilling phase to the completion phase or in well workover operations. The extremely dense brine solution gives the fluid its weight of 20 pounds/gallon, which makes it especially useful in holding back flammable oil and gas particles in high pressure wells. However, the high acidity and osmolarity cause corrosion and handling problems. Crews must be issued slicker suits and rubber boots because the fluid is so dehydrating. It is the electrolyte in the zinc–bromide battery. Zinc bromide solutions can be used as a transparent shield against radiation. The space between two glass panes is filled with a strong aqueous solution of zinc bromide with a very high density, to be used as a window on a hot cell. This type of window has the advantage over lead glass in that it will not darken as a result of exposure to radiation. All glass will darken slowly over time due to radiation, however this is especially true in a hot cell, where exceptional levels of radiation are present. The advantage of an aqueous salt solution is that any radiation damage will last less than a millisecond, so the shield will undergo self-repair.

In the laboratory In organic chemistry anhydrous ZnBr2 is sometimes used as a Lewis acid.

Safety Safety considerations are similar to those for zinc chloride, for which the toxic dose for humans is 3–5 g.

See also Zinc chloride Zinc fluoride Zinc iodide Cadmium bromide

References

Illustrations

Worked examples

Example 1 — a first encounter with Zinc bromide

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

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

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

Frequently asked questions

What is Zinc bromide in simple terms?

Why does Zinc 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 Zinc 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 Zinc bromide.