Phosphorus-Oxide

Facts on Phosphorus Oxide Include the Following:

1. Phosphorus oxide is a glass former although it is not a substitute for silica in making glass. Phosphorus remains suspended in silica glass but is separated from the silica. When isolated phosphorus is toxic and has a melting point of 580 degrees Celsius, however, it is usually combined with calcium oxide in tri-calcium phosphate (synthetic bone ash). Calcium oxide does the fluxing and phosphorous oxide the glass forming. When used in small amounts, phosphorus oxide, forms very small evenly dispersed particles that create a light reflecting quality called colloidal capacity. This makes it useful for creating many surface glazes. When used in trace amounts while being used for surface glazing it gives off a slightly bluish hue. When used in larger amounts it will opacify and create a soft mottling effect in the glaze.

2. Phosphorus oxide has a rather high contraction and expansion rate, is quite soluble in water and has low viscosity and surface tension. Sources of soluble phosphorus oxide include wood ash, calcined cattle bones, synthetic bone ash and plant ash. Insoluble phosphorus sources include the lithium mineral amblygonite.

3. Phosphorus Trioxide is a white crystalline solid that has a garlic like smell which is quite poisonous. It tends to oxidise slowly when exposed to air and will inflame when heated to a temperature of 70 degrees Celsius producing phosphorus acid. It will dissolve slowly in cold water.

4. Phosphorus Pentoxide is a white flocculent powder that can be created by heating elemental phosphorus in excess oxygen. It is quite stable and regarded as being a poor oxidising agent. When dropped into water it will make a hissing sound, this liberates heat and forms an acid. It is highly regarded as a drying agent for gasses and for removing water from many compounds because of its affinity with water.

Last Century Phosphorus Pentoxide was Mainly Used to Make Phosphoric Acid
For most of last century Phosphorus Pentoxide was widely used in the supply of concentrated phosphoric acid. This thermal process involved burning white phosphorus that was dissolved in a diluted phosphoric acid to produce concentrated acid. The current “wet phosphoric acid process” eventually replaced the former “thermal process.” The means there is now no need to produce any white phosphorus to begin the process.

Phosphorus is Never Found as a Free Element
The mineral phosphorus is nearly always present in its oxidised state in the form of inorganic phosphate rocks. It is never found as a free element because of its high reactivity but exists in its elemental form as either red phosphorus or white phosphorus. White phosphorus was first produced in 1669 when it was noticed it produced a faint glow when exposed to oxygen. The name phosphorus is derived from the Greek language meaning “light bearer.” The glow from white phosphorus is the phosphorus oxidising.

Most phosphorus compounds are used as fertilisers but it is also used in detergents, nerve agents, pesticides and in the making of matches.