Chromium (IV) oxide
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| __ Cr 4+ __ O 2− | |||||||||||||||||||
| General | |||||||||||||||||||
| Surname | Chromium (IV) oxide | ||||||||||||||||||
| other names |
Chromium dioxide |
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| Ratio formula | CrO 2 | ||||||||||||||||||
| Brief description |
brown to black solid |
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| properties | |||||||||||||||||||
| Molar mass | 83.99 g mol −1 | ||||||||||||||||||
| Physical state |
firmly |
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| density |
4.89 g cm −3 |
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| Melting point |
Decomposes above 375 ° C |
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| solubility |
almost insoluble in water |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | |||||||||||||||||||
Chromium (IV) oxide (chemical formula CrO 2 ) is the oxide of tetravalent chromium .
Extraction and presentation
It was first synthesized by Norman L. Cox, a chemist at DuPont , by decomposing chromium (VI) oxide in the presence of water at temperatures around 500 ° C and a pressure of 200 MPa.
properties
Chromium (IV) oxide is a brown to black solid. It crystallizes in a tetragonal rutile structure.
use
The ferromagnetic and electrically conductive crystals are needle-shaped, which makes them suitable for use as magnetic pigments in magnetic tapes . Commercially, it was launched by DuPont as recording material under the brand name Crolyn in the late 1960s .
Individual evidence
- ↑ Entry on chromium oxides. In: Römpp Online . Georg Thieme Verlag, accessed on June 13, 2014.
- ↑ a b c d e Entry on chromium (IV) oxide in the GESTIS substance database of the IFA , accessed on May 27, 2015 (JavaScript required)