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The last one is pyrophosphate [P 2 O 7] 4−. The pyrophosphates are mostly water-soluble. Likewise, tripolyphosphoric acid H 5 P 3 O 10 yields at least five anions [H 5−k P 3 O 10] k−, where k ranges from 1 to 5, including tripolyphosphate [P 3 O 10] 5−. Tetrapolyphosphoric acid H 6 P 4 O 13 yields at least six anions, including ...
P 4 + 4 OH − + 4 H 2 O → 4 H 2 PO − 2 + 2 H 2. Any phosphites produced in this step can be selectively precipitated out by treatment with calcium salts. The purified material is then treated with a strong, non-oxidizing acid (often sulfuric acid) to give the free hypophosphorous acid: H 2 PO − 2 + H + → H 3 PO 2. HPA is usually ...
Solid HP(O)(OH) 2 has tetrahedral geometry about the central phosphorus atom, with a P−H bond of 132 pm, one P=O double bond of 148 pm and two longer P−OH single bonds of 154 pm. In common with other phosphorus oxides with P−H bonds (e.g. hypophosphorous acid and dialkyl phosphites ), [ 2 ] it exists in equilibrium with an extremely minor ...
Hypophosphoric acid is a mineral acid with the formula H 4 P 2 O 6, with phosphorus in a formal oxidation state of +4. In the solid state it is present as the dihydrate, H 4 P 2 O 6 ·2H 2 O. In hypophosphoric acid the phosphorus atoms are identical and joined directly with a P−P bond.
In both cases the phosphoric acid solution usually contains 23–33% P 2 O 5 (32–46% H 3 PO 4). It may be concentrated to produce commercial-or merchant-grade phosphoric acid, which contains about 54–62% P 2 O 5 (75–85% H 3 PO 4). Further removal of water yields superphosphoric acid with a P 2 O 5 concentration above 70% (corresponding to ...
Some phosphorus oxoacids have two or more P atoms in different oxidation states. One example is Isohypophosphoric acid, H 4 P 2 O 6 (or H(OH)(O)P−O−P(O)(OH) 2), a tetraprotic acid and isomer of hypophosphoric acid, containing P in oxidation state +3 and +5; Phosphoric anhydride P 4 O 10 Some phosphoric acids
Element Negative states Positive states Group Notes −5 −4 −3 −2 −1 0 +1 +2 +3 +4 +5 +6 +7 +8 +9 Z; 1 hydrogen: H −1 +1: 1 2 helium: He 0 18
At pH 1 or lower, the phosphoric acid is practically undissociated. Around pH 4.7 (mid-way between the first two pK a values) the dihydrogen phosphate ion, [H 2 PO 4] −, is practically the only species present. Around pH 9.8 (mid-way between the second and third pK a values) the monohydrogen phosphate ion, [HPO 4] 2−, is the only species ...