VANADIUM(V) OXIDE - (1314-62-1)

Introduction

Name: vanadium(V) oxide; vanadium pentoxide
* IUPAC
CAS Number: 1314-62-1
Chemical Formula: V2O5
Molar Mass: 181.88 g
Mass Percent: V 56.016 %; O 43.983 % 

Classification

• inorganic

Uses/Function

• "As catalyst for the oxidation of SO2 to SO3, alcohol to acetaldehyde, etc.; for the manuf[acturing] of yellow glass; inhibiting ultraviolet light transmission in glass; depolarizer; as developer in photography; in form of ammonium vanadate as mordant in dyeing and printing fabrics and in manuf[acturing] of aniline black." 1

• "An important example [heterogeneous catalysis] is the vanadium pentoxide catalyst used in the contact process for the oxidation of SO2 to SO3 at 400 to 600°C. In practice, the V2O5 is used with a K2SO4 promoter in the pores of an inert support material, and the mixture is molten under the reaction conditions. (V2O5 melts at 690°C, but the fusion point of the mixture is lower.) However, such cases are exceptional." 2

• "The first step [of the contact process] is exothermic air oxidation of SO2 catalyzed by vanadium pentoxide (V2O5) or platinum." 3

• "Sol-gel-derived films can also serve to provide protective coverings, flat outer layers for microrough surfaces, or thin dielectric layers. "Spin-on glasses" have been developed for these applications. Some films can change color under an applied EMF (e.g., TiO2 turns blue at ~ 2 V, while brown {V2O5 + xM+ + xe-}, where M is an alkali metal, goes to blue MxV2O5), and this effect can be utilized in making electrochromic displays." 4

Physical Properties

Melting Point:*
670°C 5 = 943.15 K = 1238°F
Boiling Point:*
1800°C 5 = 2073.15 K = 3272°F
Density (g/cm3):
3.35 at room temperature/pressure 5
* - 1 atm pressure
† - decomposes

Solubility

Qualitative:
insoluble:  5
soluble:  • 5
very soluble:  5

Bonding

Bonding: ionic
Ionic Character: 54.85 %

Thermochemistry

ΔHf° (s): -370.6 kcal/mol 6 = -1,550.59 kJ/mol
S° (s): 31.3 cal/(mol•K) 7 = 130.96 J/(mol•K)
ΔGf° (s): -339.3 kcal/mol 8 = -1,419.63 kJ/mol

For More Information

Sources

(1) - 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 9987.
(2) - Swaddle, T.W. Inorganic Chemistry; Academic Press: San Diego, 1997; p 115.
(3) - Swaddle, T.W. Inorganic Chemistry; Academic Press: San Diego, 1997; p 194.
(4) - Swaddle, T.W. Inorganic Chemistry; Academic Press: San Diego, 1997; p 415.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4-93.
(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.