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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 ...
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 ...
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 ...
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 ...
It is a conjugate acid of phosphate [PO 4] 3-and a conjugate base of dihydrogen phosphate [H 2 PO 4] −. It is formed when a pyrophosphate anion [P 2 O 7] 4− reacts with water H 2 O by hydrolysis, which can give hydrogenphosphate: [P 2 O 7] 4− + H 2 O ⇌ 2 [HPO 4] 2−
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 ...
The disodium salt can be passed through an ion exchange column to form the acid dihydrate, H 4 P 2 O 6 ·2H 2 O. [2] The anhydrous acid can be formed by vacuum dehydration over P 4 O 10 or by the reaction of H 2 S on lead hypophosphate, Pb 2 P 2 O 6. [1] Hypophosphoric acid is tetraprotic with dissociation constants pK a1 = 2.2, pK a2 = 2.8, pK ...
The second and third pK a 's of phosphoric acid, pK a2 and pK a3, are 7.2 and 12.37, respectively. It follows that HPO 2− 4 and PO 3− 4 are sufficiently basic to serve as ligands. The examples below confirm this expectation.