SILICON CARBIDE - (409-21-2)

Introduction

Name: silicon carbide
* IUPAC
CAS Number: 409-21-2
Chemical Formula: SiC
Molar Mass: 40.0962 g
Mass Percent: Si 70.045 %; C 29.954 % 

Classification

• inorganic

Uses/Function

• "Known as carborundum, a major industrial abrasive and a highly refractory ceramic for tough, high-temperature uses. Can be doped to form a high-temperature semiconductor." 1

• "Polishing glass, granite; smoothing bisque ware; in sharpening-stones; abrasive; manuf[acturing] porcelain, "emery" paper and wheels, shoe soles, refractory brick, furnance linings; anti-skid pavements; in semiconductor technology." 2

• "A pebble bed nuclear reactor is schematically depicted as a funnel-shaped container through which tennis-ball size "pebbles" of fuel are circulated. Each pebble is made of graphite and carbon and contains about 15,000 kernels of fuel. Each kernel has a core of uranium that is coated with a layer each of porous carbon, pyrolytic carbon (which is similar to graphite), silicon carbide, and then a second layer of pyrolytic carbon. These layers are used to moderate the speed of neutrons, helping to control the nuclear reactions of the fuel, and to provide a fireproof seal." 3

Physical Properties

Melting Point:*
2830°C 4 = 3103.15 K = 5126°F

Density (g/cm3):
3.16 at room temperature/pressure 5
* - 1 atm pressure

Solubility

Qualitative:
insoluble:  • 5

Bonding

Bonding: polar covalent
Ionic Character: 19.70 %

Thermochemistry

ΔHf° (s beta cubic): -17.5 kcal/mol 6 = -73.22 kJ/mol
ΔHf° (s alpha hexagonal): -17.1 kcal/mol 6 = -71.55 kJ/mol
ΔHf° (g): 147 kcal/mol 6 = 615.05 kJ/mol
S° (s beta cubic): 3.97 cal/(mol•K) 7 = 16.61 J/(mol•K)
S° (s alpha hexagonal): 3.94 cal/(mol•K) 7 = 16.48 J/(mol•K)
S° (g): 56.55 cal/(mol•K) 7 = 236.61 J/(mol•K)
ΔGf° (s beta cubic): -16.9 kcal/mol 8 = -70.71 kJ/mol
ΔGf° (s alpha hexagonal): -16.5 kcal/mol 8 = -69.04 kJ/mol
ΔGf° (g): 132 kcal/mol 8 = 552.29 kJ/mol

Safety Information

NFPA 704 Ratings:
Health: 1 - Exposure would cause irritation with only minor residual injury.
Flammability: 0 - Will not burn.
Reactivity: 0 - Normally stable, even under fire exposure conditions, and is not reactive with water.

For More Information

Sources

(1) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill: New York, 2006; p 575.
(2) - The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 13th ed.; Budavari, S.; O'Neil, M.J.; Smith, A.; Heckelman, P. E.; Kinneary, J. F., Eds.; Merck & Co.: Whitehouse Station, NJ, 2001; entry 8566.
(3) - Langston, Lee S. A Path for Nuclear Power. American Scientist. 2013, 102, 91.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2003; p 4-82.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4-82.
(6) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(7) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(8) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.