Microsoft Word - WaterChemistry

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Side products from this production include ferrophosphorus, a crude form of Fe 2 P,
resulting from iron impurities in the mineral precursors. The silicate slag is a useful
construction material.

The fluoride is sometimes recovered for use in water fluoridation. More problematic is a
"mud" containing significant amounts of white phosphorus. Production of white
phosphorus is conducted in large facilities in part because it is energy intensive. The white
phosphorus is transported in molten form.

Some major accidents have occurred during transportation, train derailments at
Brownston, Nebraska and Miamisburg, Ohio led to large fires. The worst incident in recent
times was an environmental one in 1968 when the sea became contaminated due to
spillages and/or inadequately treated sewage from a white phosphorus plant at Placentia
Bay, Newfoundland.

Another process by which elemental phosphorus is extracted includes applying at high
temperatures (1500 °C):

2 Ca 3 (PO 4 ) 2 + 6 SiO 2 + 10 C → 6CaSiO 3 + 10 CO + P 4

Thermphos International is Europe's only producer of elemental phosphorus with the
annual capacity of 80,000 t provided by a plant at Vlissingen, the Netherlands.

Compounds
Oxoacids of Phosphorus
Phosphorous oxoacids are extensive, often commercially important, and sometimes
structurally complicated.

They all have acidic protons bound to oxygen atoms and some have nonacidic protons
that are bonded directly to phosphorus. Although many oxoacids of phosphorus are
formed, only nine are important, and three of them, hypophosphorous acid, phosphorous
acid, and phosphoric acid, are particularly important ones.

Oxidation

state

Formula Name

Acidic

protons Compounds

+1 HH 2 PO 2 Hypophosphorous acid 1 acid, salts

+3 H 2 HPO 3 Phosphorous acid 2 acid, salts

+3 HPO 2 metaphosphorous acid 1 salts

+3 H 3 PO 3 (ortho)phosphorous

acid

3 acid, salts

+5 (HPO 3 )n metaphosphoric acids n salts (n=3,4,6)

+5 H(HPO 3 )nOH polyphosphoric acids n+2 acids, salts (n=1-

6)

+5 H 5 P 3 O 10 tripolyphosphoric acid 3 salts

+5 H 4 P 2 O 7 pyrophosphoric acid 4 acid, salts

+5 H 3 PO 4 (ortho)phosphoric acid 3 acid, salts