Phosphotungstic acid
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| Phosphotungstic acid | |
|---|---|
| Image:Phosphotungstic acid.jpg | |
| General | |
| Systematic name | ? |
| Other names | ? |
| Molecular formula | ? |
| SMILES | ? |
| Molar mass | ?.?? g/mol |
| Appearance | ? |
| CAS number | [?-?-?] |
| Properties | |
| Density and phase | ? g/cm3, ? |
| Solubility in water | ? g/100 ml (?°C) |
| Melting point | ?°C (? K) |
| Boiling point | ?°C (? K) |
| Acidity (pKa) | ? |
| Basicity (pKb) | ? |
| Chiral rotation [α]D | ?° |
| Viscosity | ? cP at ?°C |
| Structure | |
| Molecular shape | ? |
| Coordination geometry |
? |
| Crystal structure | ? |
| Dipole moment | ? D |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | ? |
| NFPA 704 | |
| Flash point | ?°C |
| R/S statement | R: ? S: ? |
| RTECS number | ? |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Other anions | ? |
| Other cations | ? |
| Related ? | ? |
| Related compounds | ? |
| Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references |
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Phosphotungstic acid (PTA), tungstophosphoric acid, or tungsten hydrogen oxide phosphate (HPW), is a ... with chemical formula 12 WO3 . H3PO4 . x H2O. Its CAS number is [12067-99-1] [1].
EPTA is the name of ethanolic phosphotungstic acid, its alcohol solution used in biology.
It has the appearance of small, colorless-grayish or slightly yellow-green crystals, with melting point 89 °C (24 H2O hydrate). It is odorless and well soluble in water (200 g/100 ml). It is not especially toxic, but it is a mild acidic irritant.
Phosphotungstic acid is the strongest of heteropolyacids. Its conjugate base is the PW12O403- anion. [2]
Phosphotungstic acid is used in histology as a component for staining of cell specimens, often together with haematoxylin as PTAH. It binds to fibrin, collagen, and fibres of connective tissues, and replaces the anions of dyes from these materials, selectively decoloring them.
Phosphotungstic acid is electron dense, opaque for electrons. It is a common negative stain for viruses, nerves, polysaccharides, and other biological tissue materials for imaging by a transmission electron microscope.
