Oxoacids of Phosphorus

Oxoacids are acids that contain the element oxygen in their composition. Phosphorus is known to combine with other elements to generate oxoacids. Examples include H3PO4, H3PO3, and others. In the phosphorus oxoacids, the phosphorus atom is surrounded by four additional atoms in a tetrahedral arrangement. In general, it is known that all of these acids create at least one P-OH bond and one P=O bond when exposed to water.

When Phosphorus’ oxidation state is less than ‘+5’, the bonds P–P or P–H are found in addition to the bonds P=O and P-OH in oxoacids of Phosphorus, where the oxidation state of Phosphorus is less than ‘+5’. In general, these acids are observed to be disproportionately associated with lower and greater oxidation states, respectively. Consider the case in which the phosphorus acid is heated, resulting in the formation of phosphine and phosphoric acid.

4H3PO3→3H3PO4+PH3

Phosphorus Oxoacids That Are Commonly Used

Phosphorus acid,H3PO3

Phosphorous acid is a diprotic acid, meaning it has two protons. That is, it ionises two protons at the same time. HPO(OH)2 is a structural formula that describes the compound better than any other. The phosphorous acid is produced by hydrolysis of phosphorus trichloride in the presence of either steam or acids.

PCl3+3H2O→HPO(OH)2+3HCl

Phosphoric acid,H3PO4

Phosphoric acid is a triprotic acid, which means it has three oxidising agents. This means it ionises three protons at the same time. When pure, it is a solid at room temperature and pressure, and it is a non-toxic acid when mixed with other substances. Phosphoric acid is produced by combining sulfuric acid with tricalcium phosphate rock and heating the mixture.

Ca5(PO4)3X+5H2SO4+10H2O→3H3PO4+5CaSO4.2H2O+HX

Here, X can be the F, Cl, Br, and OH.

MetaPhosphoric(HPO3)n

This acid is formed by heating orthophosphoric acid to about 850 degrees Celsius. A monomer of metaphosphoric acid is not known, although it does exist in the form of cyclic trimers, cyclic tetramers, or polymers.

H3PO4→HPO3+H2O

Hypophosphoric Acid,H4P2O6

Sodium chlorite is used to produce hypophosphoric acid, which is formed through the controlled oxidation of red Phosphorus. Once the disodium salt of the acid has been generated, it is transported through a cation exchanger, where it eventually results in the formation of hypophosphoric acid. A tetrabasic nature can be found in the acid.

2P+2NaClO2+2H2O→Na2H2P2O6+2HCl

Na2H2P2O6+2H−−(resin)→H4P2O6+2Na(resin)

Pyrophosphoric Acid, H4P2O7

Tetrabasic acid is formed when orthophosphoric acid is heated to about 250°C, resulting in the formation of orthophosphoric acid.

2H3PO4→H4P2O7+H2O

Orthophosphoric Acid,H3PO4

When the phosphoric acid (P4O10) is treated with bubbled water, orthophosphoric acid is produced. This acid is tribasic in nature.

P4O10+6H2O→4H3PO4

Acidic strength

The following is the acidic strength order of the phosphorus oxyacids: H3PO2, H3PO3, and H3PO4.

It is H3PO4 > H3PO3 > H3PO2 in the strength of the oxoacids in the phosphorus acidity hierarchy.

In the first example, all hydrogen atoms are bonded to an oxygen atom as an OH group, which allows hydrogen to be released as protons with relative ease in the second situation. As a result, the acidity of phosphorus oxyacids will be at their greatest level. Similarly, in the second example, two hydrogen atoms are bonded to the oxygen atoms, while the third hydrogen atom is attached to the P atom, which is unable to emit a proton because of the hydrogen bonding.

To finish off, just one hydrogen atom is bonded to oxygen, while the other two hydrogen atoms are attached straight to P, which means that they will not come out as protons in the third scenario. In addition, only one hydrogen can be produced in the form of a proton. Consequently, the acidity of a protonic acid is determined by the ease with which a proton is released from the species. So the resulting order is the one that has been specified previously.

Oxoacids of Phosphorus Have a Basic Characteristic

The basicity of phosphorus oxoacids is defined as the number of ionizable H+ ions or protons present in the acid in which it is present.

Despite the fact that Oxoacids of Phosphorus have three hydrogen atoms in their structure, only the ones that are immediately linked to the Oxygen (O) atom will be easily ionised. However, there are only two of these H atoms in existence. As a result, the basicity of phosphorus oxoacids is equal to three.

Oxoacids of Phosphorus Have a Variety of Applications

•Phosphorus is utilised in the manufacturing of HI and HBr as a substitute for sulphuric acid, which are just a few of the applications for phosphorus oxoacids, among others.

•In the manufacture of soft drinks, it is used as a souring ingredient to enhance the flavour.

•Sodium phosphate salts, ammonium phosphate salts, and potassium phosphate salts are all made from this compound.

•It is a chemical compound that is employed in the production of phosphatic fertilisers.

Conclusion

Oxoacids are acids that contain the element oxygen in their composition. Phosphorus is known to combine with other elements to generate oxoacids.Phosphorous acid is a diprotic acid, meaning it has two protons. That is, it ionises two protons at the same time. HPO(OH)2 is a structural formula that describes the compound better than any other.Phosphoric acid is a triprotic acid, which means it has three oxidising agents. This means it ionises three protons at the same time.Sodium chlorite is used to produce hypophosphoric acid, which is formed through the controlled oxidation of red Phosphorus.The basicity of phosphorus oxoacids is defined as the number of ionizable H+ ions or protons present in the acid in which it is present.Phosphorus is utilised in the manufacturing of HI and HBr as a substitute for sulphuric acid, which are just a few of the applications for phosphorus oxoacids, among others.