Phosphates, Vanadates, Arsenates, Tungstates, and Molybdates

1
Phosphates, Vanadates, Arsenates, Tungstates, and
Molybdates

• GLY 4200
• Lab 9 - Fall, 2012

2
Phosphates, Vanadates, and Arsenates

• Groups are tetrahedral, with strong bonding with
  in the group
• PO43-, VO43-, AsO43-
• What is the charge on the cation?

3
Apatite

• Most important phosphate mineral
• Major ore of phosphorous
• Ca5(PO4)3(F,Cl, OH)
• Occurs in three varieties
• Fluor
• Chlor
• Hydroxy

4
Phosphates and Radiation

• Uranium occurs in many phosphate group minerals,
  making them radioactive
• The mining of phosphate ores often releases
  radioactivity into the environment
• Houses built on or around phosphate gangue
  material may be plagued by high radon
  concentrations as a result

5
Tungstates and Molybdates

• Cations are quite large
• W and Mo have nearly identical radii why?
• Anionic groups are distorted square planar rather
  than tetrahedral

6
Extensive Partial Solid Solution

• Involves both cations and anionic groups
• Cation substitution
• Wolframite series complete solid solution
• FeWO4, Ferberite
• MnWO4, Huebnerite
• Wulfenite PbMoO4
• Partial series to Powellite, CaMoO4

7
Anionic Substitution

• Partial solid solution
• CaWO4, Scheelite
• CaMoO4, Powellite

8
Text Reference

• See chapter 17 in the text for more information
  on phosphates, vanadates, arsenates, tungstates,
  and molybdates, pp. 405-406 and 425-433