Phosphoric

Phosphoric, in chemical usage, most often refers to phosphoric acid, a colorless, odorless, syrupy liquid at room temperature with the formula H3PO4. It is a weak, triprotic acid that dissociates in water in three stages, with pKa values near 2.15, 7.20, and 12.37. It is highly soluble in water and is hygroscopic, readily forming solutions of various concentrations.

Industrial production of phosphoric acid occurs mainly via two routes. The wet process reacts phosphate rock with sulfuric acid, yielding phosphoric acid and calcium sulfate as a byproduct (gypsum). The resulting solution is concentrated to produce fertilizer-grade acids of about 40–54% H3PO4, which are further used to manufacture phosphate fertilizers or chemicals. The thermal process, by contrast, starts with elemental phosphorus and produces anhydrous phosphoric acid by hydrolysis of phosphorus pentoxide; this method yields higher-purity acid used for industrial applications but at greater cost.

Major uses are dominated by agriculture and food processing. The acid is the primary raw material for soluble phosphate fertilizers such as monoammonium phosphate (MAP), diammonium phosphate (DAP), and triple superphosphate (TSP). It is also employed in the production of many phosphates used in fertilizers and animal feeds. In the food industry, phosphoric acid serves as an acidity regulator (often labeled as E338) and is used to acidify beverages and some processed foods. It also finds use in metal treatment, dentin etching in dentistry, and various cleaning formulations.

Safety and environmental considerations include its corrosive nature, potential to cause severe skin and eye irritation, and respiratory hazards in mist forms. Environmental release can contribute to nutrient pollution and eutrophication. Proper handling, storage, and disposal are essential in industrial and consumer contexts.