ZINC OXIDE - (1314-13-2)

Introduction

Name: zinc oxide
* IUPAC
CAS Number: 1314-13-2
Chemical Formula: ZnO
Molar Mass: 81.4084 g
Mass Percent: Zn 80.346 %; O 19.653 % 

Classification

• inorganic

Uses/Function

• "Zinc oxide is used in making rubber, where it imparts desirable characteristics to the material. Zinc oxide is also used as a pigment in white paint and in enamels and glazes.

Zinc oxide (as well as certain other materials) is also used as a photoconductive surface in photocopiers. A photoconductive material becomes electrically conducting when exposed to light. The zinc oxide surface in the copier is electrically charged, then exposed to a light image from a printed document. Lighted areas of the photoconducting surface become electrically conducting, so that the electrical charge in these areas is drained away. Dark areas remain electrically charged, however. When a black powder, called the toner, is pread over the zinc oxide surface, it sticks to the electrically charged areas, producing an image of the document. This image is then transferred with heat to a sheet of paper." 1

• "As pigment in white paints instead of lead carbonate; in cosmetics, driers, quick-setting cements; with syrupy phosphoric acid or ZnCl2 in dental cements; manuf[acturing] opaque glass and certain types of transparent glass; manuf[acturing] enamels, automobile tires, white glue, matches, white printing inks, porcelains, zinc green; as a reagent in analytical chemistry; in electrostatic copying paper; as flame retardant; in electronics as semiconductor. Therapeutic: Astringent; topical protectant; ultraviolet screen. Therapeutic (Veteterinary): Antiseptic; astringent; topical protectant." 2

Physical Properties

Melting Point:*
1974°C 3 = 2247.15 K = 3585.2°F

Density (g/cm3):
5.67 2
* - 1 atm pressure

Bonding

Bonding: ionic
Ionic Character: 54.24 %

Thermochemistry

ΔHf° (s): -83.24 kcal/mol 4 = -348.28 kJ/mol
S° (s): 10.43 cal/(mol•K) 5 = 43.64 J/(mol•K)
ΔGf° (s): -76.08 kcal/mol 6 = -318.32 kJ/mol

Reactions

Safety Information

NFPA 704 Ratings:
Health: 2 - Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury.
Flammability: 1 - Must be heated before ignition can occur. Flash point over 93°C (200°F).
Reactivity: 0 - Normally stable, even under fire exposure conditions, and is not reactive with water.
Special Hazard: W - Reacts with water in an unusual or dangerous manner.

For More Information

Wikipedia
Journals:
S. R. Pinnell et. al., Dermatol. Surg. 26, 309 (2000)

Sources

(1) - Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; pp 782-783.
(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 10200.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4-95.
(4) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(5) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(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) - Swaddle, T.W. Inorganic Chemistry; Academic Press: San Diego, 1997; p 385.