|
There are various kinds of phosphoric acids and phosphates. Of the many phosphorus oxoacids, the phosphoric acids constitute the largest and most diverse group. The simplest phosphoric acid series begins with monophosphoric (orthophosphoric) acid, continues with many oligophosphoric acids such as diphosphoric (pyrophosphoric) acid and concludes in the polyphosphoric acids. But, phosphoric acid units can bind together into rings or cyclic structures, chains (catenas), or branched structures, with various combinations possible. Each of these can form phosphates (salts or esters of phosphoric acids). ==Orthophosphoric acid== (詳細はcompound of a series of phosphoric acids is sometimes called by its common name, orthophosphoric acid, but more often called by its IUPAC name, simply phosphoric acid, by both non-technical people and even many chemists. It has also been called monophosphoric acid. The chemical formula of orthophosphoric acid is H3PO4 and its chemical structure is shown in the illustration below. Two or more orthophosphoric acid molecules can be joined by condensation into larger molecules by elimination of water. This way, a series of polyphosphoric acids can be obtained. Image:Phosphoric-acid-3D-vdW.png| H3PO4 Image:Pyrophosphoric-acid-3D-vdW.png| H4P2O7 Image:Tripolyphosphoric-acid-3D-vdW.png| H5P3O10 Image:Tetrapolyphosphoric-acid-3D-vdW.png| H6P4O13 Image:Trimetaphosphoric-acid-3D-vdW.png| H3P3O9 Image:Phosphorus-pentoxide-3D-vdW.png| P4O10 ==Orthophosphate== Orthophosphoric acid has three hydrogen atoms bonded to oxygen atoms in its structure. All three hydrogens are acidic to varying degrees and can be lost from the molecule as H+ ions (alternatively referred to as protons). When all three H+ ions are lost from orthophosphoric acid, an orthophosphate ion (PO43−) is formed. Orthophosphate is the simplest in a series of phosphates, and is usually just called phosphate by both non-technical people and many chemists alike; see a separate article on phosphate for details. Because orthophosphoric acid can undergo as many as three dissociations or ionizations (losses of H+ ions), it has three acid dissociation constants called Ka1, Ka2, and Ka3. Another way to provide acid dissociation constant data is to list pKa1, pKa2, and pKa3 instead. Orthophosphate is in a sense the triple conjugate base of phosphoric acid and has three related basicity constants, Kb1, Kb2, and Kb3, which likewise have corresponding pKb1, pKb2, and pKb3 values. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Phosphoric acids and phosphates」の詳細全文を読む スポンサード リンク
|