Zinc bromide
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| Names | |
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| IUPAC name
Zinc bromide
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| Other names
Zinc(II) bromide,
Zinc dibromide | |
| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.028.836 |
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| 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 |
| Boiling point | 697 °C |
| 311 g/100 mL (0 °C) 447 g/100 mL (20 °C)[1] 538 g/100 mL (100 °C)[2] | |
| Solubility | very soluble in alcohol, ether, acetone, tetrahydrofuran |
Refractive index (nD)
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1.5452 |
| Hazards | |
| NFPA 704 (fire diamond) | |
| Flash point | Non-flammable |
| Related compounds | |
Other anions
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Zinc fluoride, Zinc chloride, Zinc iodide |
Other cations
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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).
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Zinc bromide (ZnBr2) is a chemical compound of zinc and bromine. Its shares many properties with zinc chloride, ZnCl2, namely a high solubility in water forming acidic solutions, and solubility in organic solvents. It is hygroscopic and forms a hydrate ZnBr2.2H2O.
ZnBr2 can be prepared by reacting (double displacement) barium bromide and zinc sulfate to produce the insoluble barium sulfate along with zinc bromide or the reaction of HBr and zinc metal:[1]
- BaBr2 + ZnSO4 → BaSO4 + ZnBr2
- Zn + 2 HBr → ZnBr2 + H2
The structure of crystalline ZnBr2 has the same unusual structure as ZnI2. Zinc atoms are tetrahedrally coordinated, and groups of four of these tetrahedra share three vertices to form “super-tetrahedra” of composition {Zn4Br10}, which are linked by their vertices to form a three dimensional structure.[3]
Molecular, vapour phase, ZnBr2 is linear in accordance with VSEPR theory with a Zn-Br bond length of 221 pm.[4]
The dihydrate ZnBr2.2H2O also has a usual structure and should be formulated as Zn(H2O)6 Zn2Br6, where the Zn2Br62− ion has bromine bridges linking the two zinc atoms, and has a similar structure to the dimeric form of aluminium bromide, Al2Br6.[5]
Uses
- Organic chemistry as a Lewis acid.
- As a transparent shield against radiation.[1] [2] Two glass panes filled with a strong aqueous solution of zinc bromide has a very high density, which can then 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.
- The Zinc bromide battery.
- Used in oil and natural gas wells to displacing drilling mud when transistioning from the drilling phase to the completion phase or in well workover operations. The extremely heavy dense brine solution gives the fluid it's 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 osmilarity cause high corrosion and handling problems. Crews must be issued slicker suits and rubber boots because the salt in the fluid removes water from live tissue, leather boots, and gloves via osmosis. The HSE concerns must be weighed carefully against it's advantages when using this fluid.
See also
References
- ^ a b Pradyot Patnaik, 2003, Handbook of Inorganic Chemicals, McGraw-Hill Professional, ISBN 0070494398
- ^ http://chemicalland21.com/industrialchem/inorganic/ZINC%20BROMIDE.htm
- ^ Crystal structure of anhydrous zinc bromide, Chung Chieh , White M. A., Zeitschrift für Kristallographie, 1984, 166, 3-4, 189-197
- ^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
- ^ Zinc bromide dihydrate ZnBr2.2H2O: a double-salt structure, R. Duhlev, I. D. Brown and R. Faggiani, Acta Cryst. (1988). C44, 1696-1698 ,doi:10.1107/S0108270188006584
- ^ ORO Recycling of Excess Zinc Bromide
- ^ The Georgia Institute of Technology High-Dose Gamma Irradiation Facility
- ^ http://www.glossary.oilfield.slb.com/Display.cfm?Term=zinc%20bromide
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