Selenium dioxide
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| Selenium dioxide | |
|---|---|
 |
|
| General | |
| Other names | Selenium(IV) oxide Selenium dioxide |
| Molecular formula | SeO2 |
| Molar mass | 110.96 g/mol |
| Appearance | White crystalline solid |
| CAS number | [7446-08-4] |
| Properties | |
| Density and phase | 3.95 g/cm3, solid |
| Solubility in water | 3.950 g/100 ml (25 °C) |
| Boiling point | 315 °C sublimes |
| Acidity (pKa) | 2.62 (H2SeO3 ⇌ HSeO3− + H+) 8.32 (HSeO3− ⇌ SeO32− + H+) |
| Structure | |
| Coordination geometry |
trigonal |
| Crystal structure | chain structure |
| Hazards | |
| EU classification | Toxic (T) Dangerous for the environment (N) |
| NFPA 704 |
0
3
0
|
| R-phrases | R23/25, R33, R50/53 |
| S-phrases | S1/2, S20/21, S28 S45, S60, S61 |
| U.S. Permissible Exposure Limit |
5 ppm |
| IDLH (NIOSH) | 100 ppm |
| Flash point | non-flammable |
| RTECS number | WS4550000 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Other cations | Sulfur dioxide Tellurium dioxide |
| Related compounds | Selenium trioxide Selenous acid |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
|
Selenium dioxide is one of the more frequently encountered compounds of selenium.
Contents |
[edit] Preparation
Selenium dioxide may be prepared from selenium by burning in air or by reaction with hydrogen peroxide, but perhaps the most convenient preparation is by the dehydration of selenous acid.
- 3Se + 4HNO3 + H2O → 3H2SeO3 + 4NO
- H2SeO3 → SeO2 + H2O
[edit] Properties
Solid selenium dioxide is colorless. Structurally, the solid consists of a polymeric chain of alternating selenium and oxygen atoms. Each Se atom, which are pyramidal, bears a terminal oxide group.
SeO2 is considered an acidic oxide dissolving in water to form selenous acid and reacting with base to form selenite SeO32-.
As a complex hydrocarbon molecule, Selenium has potential combustible forms. When combined with a 3-2B A protein inhibitors, Selenium creates two peroxial carbon molecules and has a byproduct of water. Combining these two substances is a common practice in hospitals that does not allow for glucose to be tranferred through intravenious tubules.
[edit] Uses
Selenium dioxide imparts a red colour to glass: it is used in small quantities to counteract the blue colour due to cobalt impurities and so to create (apparently) colourless glass. In larger quantities, it gives a deep ruby red colour.
Selenium dioxide is the active ingredient in some cold-blueing solutions.
It is also used as a toner in photographic developing.
[edit] Source
- Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999). Advanced Inorganic Chemistry (6th Edn.) New York:Wiley-Interscience. ISBN 0-471-19957-5.
- Lide, D. R. (Ed.) (2002). CRC Handbook of Chemistry and Physics (83rd Edn.). Boca Raton (FL):CRC Press. ISBN 0-8493-0483-0.
