Melting point: ~40℃(lit.)
Boiling point: 158℃(lit.)
Density: 1.685 g/mL at 25℃(lit.)
Vapor density: 3.4 (vs air)
Phosphoric acid is also called orthophosphoric acid (molecular structural formula H3PO4). The pure product is a colorless transparent viscous liquid or orthorhombic crystals, odorless and very sour in taste. 85% phosphoric acid is colorless, transparent or slightly light-colored, thick liquid. The melting point is 42.35°C, the specific gravity is 1.70, and the high boiling point acid can be miscible with water in any ratio. When the boiling point is 213°C (lose 1/2 of water), pyrophosphoric acid is formed. It becomes metaphosphoric acid when heated to 300°C. The relative density is 181.834. It is easily soluble in water and soluble in ethanol. Phosphoric acid is a common inorganic acid and a medium strong acid.
Mainly used in phosphate industry, electroplating, polishing industry, sugar industry, compound fertilizer, etc. Used as a sour agent, yeast nutrient, etc. in the food industry.
Industrial production methods include wet and thermal methods. The former has a lower concentration of phosphoric acid and contains more impurities, which requires purification. For example, using the ketone-alcohol mixture as the extraction system to refine wet-process phosphoric acid, through the process of extraction-washing-back-extraction and barium salt precipitation purification, qualified 85% industrial phosphoric acid has been produced. The latter produced phosphoric acid with high concentration and purity, but high power consumption, high investment and cost.