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Zinc bromide
	Zinc bromide
Names
	IUPAC name Zinc bromide
	Other names Zinc(II) bromide,; Zinc dibromide
Identifiers
CAS Number	7699-45-8 ;
3D model (JSmol)	Interactive image;
ChemSpider	22790 ;
ECHA InfoCard	100.028.836
PubChem CID	24375;
RTECS number	ZH1150000;
UNII	OO7ZBU9703 ;
CompTox Dashboard (EPA)	DTXSID8052512 ;
	InChI InChI=1S/2BrH.Zn/h21H;/q;;+2/p-2 Key: VNDYJBBGRKZCSX-UHFFFAOYSA-L ; InChI=1/2BrH.Zn/h21H;/q;;+2/p-2 Key: VNDYJBBGRKZCSX-NUQVWONBAG;
	SMILES Br[Zn]Br;
Properties
Chemical formula	ZnBr2
Molar mass	225.198 g/mol
Appearance	white crystalline powder ; hygroscopic
Density	4.20 g/cm3 (20 °C) ; 4.22 g/cm3 (25 °C)
Melting point	394 °C (741 °F; 667 K)
Boiling point	697 °C (1,287 °F; 970 K)
Solubility in water	388 g/100 mL (0 °C) ; 675 g/100 mL (100 °C, for the anhydrous material)
Solubility	very soluble in alcohol, ether, acetone, tetrahydrofuran
Refractive index (nD)	1.5452
Hazards
NFPA 704 (fire diamond)	3 0 0
Flash point	Non-flammable
Safety data sheet (SDS)	External MSDS
Related compounds
Other anions	Zinc fluoride,; Zinc chloride,; Zinc iodide
Other cations	Cadmium bromide,; Mercury(II) bromide,; Calcium bromide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Zinc bromide (Zn Br₂) is an inorganic compound with the chemical formula Zn Br₂. 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.^[2]

Production

ZnBr₂ · 2H₂O is prepared by treating zinc oxide or zinc metal with hydrobromic acid.^[1]

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.^[2] Sublimation in a stream of hydrogen bromide also gives the anhydrous derivative.^[1]

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.^[3] The dihydrate ZnBr₂ · 2H₂O can be described as ([Zn(H₂O)₆]²⁺)²([Zn₂Br₆]^2-).^[4]

Gaseous ZnBr₂ is linear in accordance with VSEPR theory with a Zn-Br bond length of 221 pm.^[5]

Uses

Zinc bromide is mainly used in servicing oil and natural gas wells, solutions of zinc bromide are used to displace drilling mud when transitioning 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.^[6]^[2]

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.^[7]

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.^[2]

References

^ ^a ^b ^c F. Wagenknecht; R. Juza (1963). "Zinc bromide". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 1. NY, NY: Academic Press. p. 1071.
^ ^a ^b ^c ^d Yoffe, David; Frim, Ron; Ukeles, Shmuel D.; Dagani, Michael J.; Barda, Henry J.; Benya, Theodore J.; Sanders, David C. (2013). "Bromine Compounds". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–31. doi:10.1002/14356007.a04_405.pub2. ISBN 978-3-527-30385-4.
^ Chieh, C.; White, M. A. (1984). "Crystal Structure of Anhydrous Zinc Bromide". Zeitschrift für Kristallographie. 166 (3–4): 189–197. Bibcode:1984ZK....166..189C. doi:10.1524/zkri.1984.166.3-4.189.
^ Duhlev, R.; Brown, I. D.; Faggiani, R. (1988). "Zinc Bromide Dihydrate ZnBr₂·2H₂O: a Double-Salt Structure". Acta Crystallographica C. 44 (10): 1696–1698. Bibcode:1988AcCrC..44.1696D. doi:10.1107/S0108270188006584.
^ Wells A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford Science Publications. ISBN 0-19-855370-6.
^ "Zinc Bromide - drilling fluids". Oilfield Glossary. Schlumberger.
^ Blaylock, D. P.; Abu-Jawdeh, E. (January 1999). "The Georgia Institute of Technology High-Dose Gamma Irradiation Facility". 32nd Annual Midyear Meeting - Creation and Future Legacy of Stockpile Stewardship Isotope Production, Applications, and Consumption. Poster Session. Albuquerque, NM: Health Physics Society.