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Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula H 3 P O 4. It is commonly encountered as an 85% aqueous solution , which is a colourless, odourless, and non- volatile syrupy liquid.
Since the ends are condensed, its formula has one less H 2 O (water) than tripolyphosphoric acid. The general formula of a phosphoric acid is H n−2x+2 P n O 3n−x+1, where n is the number of phosphorus atoms and x is the number of fundamental cycles in the molecule's structure; that is, the minimum number of bonds that would have to be ...
HPA is usually supplied as a 50% aqueous solution and heating at low temperatures (up to about 90 °C) prompts it to react with water to form phosphorous acid and hydrogen gas. H 3 PO 2 + H 2 O → H 3 PO 3 + H 2. Heating above 110 °C causes hypophosphorous acid to undergo disproportionation to give phosphorous acid and phosphine. [7] 3 H 3 PO ...
Trisodium phosphate is produced by neutralization of phosphoric acid using sodium carbonate, which produces disodium hydrogen phosphate. The disodium hydrogen phosphate is reacted with sodium hydroxide to form trisodium phosphate and water. Na 2 CO 3 + H 3 PO 4 → Na 2 HPO 4 + CO 2 + H 2 O Na 2 HPO 4 + NaOH → Na 3 PO 4 + H 2 O
A major appeal of this route is the low cost of phosphoric acid compared to phosphorus oxychloride. OP(OH) 3 + ROH → OP(OH) 2 (OR) + H 2 O. P 2 O 5 is the anhydride of phosphoric acid and acts similarly. The reaction yields equimolar amounts of di- and monoesters with no phosphoric acid.
Phosphorus pentoxide (P 4 O 10) is the acid anhydride of phosphoric acid, but several intermediates between the two are known. This waxy white solid reacts vigorously with water. This waxy white solid reacts vigorously with water.
, is the only species present. At pH 13 or higher, the acid is completely dissociated as the phosphate ion, (PO 4) 3−. This means that salts of the mono- and di-phosphate ions can be selectively crystallised from aqueous solution by setting the pH value to either 4.7 or 9.8. In effect, H 3 PO 4, H 2 (PO 4) − and H(PO 4) 2−
Monopotassium phosphate can exist in several polymorphs.At room temperature it forms paraelectric crystals with tetragonal symmetry. Upon cooling to −150 °C (−238 °F) it transforms to a ferroelectric phase of orthorhombic symmetry, and the transition temperature shifts up to −50 °C (−58 °F) when hydrogen is replaced by deuterium. [8]