Selenium - Materials / Alfa Chemistry

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Selenium

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Catalog Number

ACMA00014372

Product Name

Selenium

Category

Glass Additives

Description

Selenium is a reddish colored powder that may become black upon exposure to air. It is toxic by ingestion. It is used to manufacture electronic components and rubber.;DryPowder; DryPowder, OtherSolid; OtherSolid; PelletsLargeCrystals;GREY SOLID IN VARIOUS FORMS.;COLOURLESS COMPRESSED LIQUEFIED GAS WITH CHARACTERISTIC ODOUR.;Amorphous or crystalline, red to gray solid.;Amorphous or crystalline, red to gray solid. [Note: Occurs as an impurity in most sulfide ores.]

IUPAC Name

selenium

Molecular Weight

78.97g/mol

Molecular Formula

H2Se;Se

Canonical SMILES

[Se]

InChI

InChI=1S/Se

InChI Key

BUGBHKTXTAQXES-UHFFFAOYSA-N

Boiling Point

1265 °F at 760 mm Hg (NIOSH, 2016);685 °C;685 °C;-41 °C;1265°F;1265°F

Melting Point

392 °F (NIOSH, 2016);220.8 °C (gray selenium); vitreous selenium is transformed to gray selenium at 180 °C; alpha-form transforms to gray at temperatures above 120 °C;217 °C;-66 °C;392°F;392°F

Flash Point

Flammable gas

Density

4.28 (NIOSH, 2016);4.39 g/cu cm (alpha form); 4.809 g/cu cm (gray selenium); 4.28 g/cu cm (vitreous selenium);Relative density (water = 1): 4.8;Relative density (water = 1): 2.1 (liquid);4.28;4.28

Solubility

Insoluble (NIOSH, 2016);Insoluble;Soluble in aq potassium cyanide soln, potassium sulfite soln, dilute aqueous caustic alkali soln;Insoluble in water and alcohol;Soluble in concentrated nitric acid.;Soluble in carbon disulfide, 2 mg/100 mL at room temperature; soluble in ether;Solubility in water: none;Solubility in water, ml/100ml at 22.5 °C: 270;Insoluble

Color/Form

Selenium exists in several allotropic forms. 3 are generally recognized ... Selenium can be prepd with either amorphous or crystalline structure. ... Amorphous is either red, in powder form or black, in vitreous form. Crystalline monoclinic selenium is deep red; crystalline hexagonal form, the most stable variety, is a metallic gray.

Complexity

Corrosivity

Strongly corrosive, especially at high temperature.

Covalently-Bonded Unit Count

EC Number

231-957-4

Exact Mass

79.91652g/mol

Formal Charge

Heat of Vaporization

59.7 kJ/mol

Heavy Atom Count

ICSC Number

0072;0284

MeSH Entry Terms

Selenium;Selenium 80;Selenium-80

Monoisotopic Mass

79.91652g/mol

Other Experimental

Combines directly with hydrogen, with the halogens (excluding iodine); oxidized to selenious acid by nitric acid, to selenic acid by sulfuric acid; reduces hot aqueous soln of silver and gold salts with formation of silver selenide and metallic gold, respectively;Exhibits both photovoltaic action, where light is converted directly to electricity; exhibits photoconductive action, where electrical resistance decreases with increased illumination;Vitreous, Black selenium; dark red-brown to bluish-black solid; density = 4.28; softens at 50 to 60 °C and becomes elastic at 70 °C. Red amorphous form; density = 4.26. When freshly precipitated, reacts with water at 50 °C forming selenious acid and hydrogen. Soluble in carbon disulfide, methylene iodide, benzene or quinoline /amorphous forms/;Two monoclinic forms; dark red, transparent crystals. Melting point below 200 °C. Density (alpha-form) 4.46. Both forms are metastable and change into gray form on heating /Crystalline or red selenium/.;Crystalline selenium is a p-type semiconductor... forms binary alloys with silver, copper, zinc, lead, etc.;Selenium reacts with electropositive elements (many metals) to form selenides.;Liquid is a brownish red;Lustrous gray to black hexagonal crystals; insoluble in alcohol; very slightly soluble in carbon disulfide (2 mg/100 mL at ordinary temperature); soluble in ether; conducts electricity and rectifies alternating current; conductivity increases up to 1000 times on exposure to light; density 4.81 at 20 °C/4 °C; melting point 217 °C; Mohs' hardness: 2.0; Latent heat of fusion 16.4 cal/g; Latent heat of vaporization 20.6 kcal/mol; Linear coefficient of thermal expansion per degree C = 37X10-6; Specific heat (28 °C): 0.084 cal/g/deg C; Surface tension (217 °C): 92.5 dynes/cm; Thermal conductivity (25 °C): 0.0007-0.00183 cal/(cm)(deg C)sec. /Gray or metallic selenium/;Molar heat of fusion: 6.69 kJ/mol /Selenium (gray)/;Insoluble in ethanol; slightly soluble in ether /alpha-form/;Slightly soluble in carbon disulfide /vitreous/;Magnetic susceptibility: -25x10-6 cu cm/mol;Specific heat capacity: 0.321 J/g-K; molar heat capacity: 25.363 J/mol-K;Standard molar enthalpy of formation: 0.0 kJ/mol (gray), 6.7 kJ/mol (alpha form), 5.0 kJ/mol (vitreous); standard molar entropy: 42.4 J/mol-K (gray); molar heat capacity at constant pressure: 25.4 J/mol-K (gray);Permittivity (dielectric constant): 5.44 at 510.65 K;Electron affinity: 2.020670 eV;Ionization energy: 9.75238 eV;Very salty solution in ether; viscosity decreases with temperature;Electronegativity, Pauling scale: 2.4;Selenium combines with oxygen to form several substances that are white or colorless crystals; some selenium compounds are gases;... selenates are easily reduced to selenium. /Selenium/;Selenium Decay Pathways;Table: Natural Isotopes [Table#4965];Selenium Decay Pathways;Table: Artificial Isotopes [Table#4966]

Rotatable Bond Count

RTECS Number

VS7700000

UNII

H6241UJ22B;V91P54KPAM

UN Number

3283;3283;2202;2658;2658

Vapor Density

Relative vapor density (air = 1): 2.8

Vapor Pressure

0 mm Hg (approx) (NIOSH, 2016);1 Pa at 227 °C; 10 Pa at 279 °C; 100 Pa at 344 °C; 1 kPa at 431 °C; 10 kPa at 540 °C; 100 kPa at 685 °C;Vapor pressure, Pa at 20 °C: 0.1;Vapor pressure, kPa at 21 °C: 878;0 mmHg (approx);0 mmHg (approx)

Viscosity

221 mPa-S (= cP) at 220 °C; 70 cP at 360 °C

MSDS

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COA

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Spec Sheet

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