Sodium selenide

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Sodium selenide
Sodium-selenide-unit-cell-1992-CM-3D-balls.png
Identifiers
CAS number 1313-85-5 YesY
PubChem 73973
EC number 215-212-0
ChEBI CHEBI:77773 N
Jmol-3D images Image 1
Properties
Molecular formula Na2Se
Molar mass 124.94 g mol−1
Appearance white to red solid
Odor unpleaseant
Density 2.625 g cm−3[1]
Melting point 875 °C (1,607 °F; 1,148 K)
Solubility in water reacts with water
Structure
Crystal structure cubic
Thermochemistry
Std molar
entropy
So298
105 J/mol K
Std enthalpy of
formation
ΔfHo298
-343 kJ/mol
Related compounds
Other anions Sodium sulfide
Sodium telluride
Sodium oxide
Other cations Hydrogen selenide
Antimony selenide
Aluminum selenide
Related compounds Sodium selenite
Sodium selenate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Sodium selenide is an inorganic compound of sodium and selenium with the chemical formula Na2Se.

Preparation[edit]

This colourless solid is prepared by the reaction of selenium with a solution of sodium in liquid ammonia at -40 °C.[2]

Alternatively, sodium selenide can be prepared by the reaction of gaseous hydrogen selenide with metallic sodium at 100 °C.

Reactions[edit]

Like other alkali metal chalcogenides, this material is highly sensitive to water, easily undergoing hydrolysis to give mixtures of sodium biselenide (NaSeH) and hydroxide. This hydrolysis occurs because of the extreme basicity of the Se2- ion.

Na2Se + H2O → NaHSe + NaOH

Similarly, sodium selenide is readily oxidized to polyselenides, a conversion signaled by off-white samples.

Sodium selenide reacts with acids to produce toxic hydrogen selenide gas.

Na2Se + 2 HCl → H2Se + 2 NaCl

The compound reacts with electrophiles to produce the selenium compounds. With alkyl halides, one obtains a variety of organoselenium compounds:

Na2Se + 2 RBr → R2Se + 2 NaBr

Organotin and organosilicon halides react similarly to give the expected derivatives:

Na2Se + 2 Me3ECl → (Me3E)2Se + 2 NaCl (E = Si, Ge, Sn)

Safety[edit]

Sodium selenide should be stored and handled away from moisture and air.

References[edit]

  1. ^ David R. Lide (ed.). CRC Handbook of Chemistry and Physics (90th ed.). ISBN 978-1-4200-9084-0. 
  2. ^ Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 421.