Formula H₃PO₄, molecular weight 97.99. A colourless, transparent, viscous liquid, odourless with a sour taste, melting point 42.35 °C, converted to metaphosphoric acid at 300 °C, relative density 1.834, soluble in water and ethanol, hygroscopic and irritating to the skin. Industrial phosphoric acid is used to produce phosphate salts, for phosphating metal surfaces, for preparing electrolytic and chemical polishing baths, as a catalyst, desiccant and cleaning liquid, in phosphoric acid refractory cements and inorganic binders, and in anti-rust paints. Food-grade acid serves as an acidulant and yeast nutrient in seasonings, canned foods and soft drinks, and in brewing as a yeast nutrient that suppresses spoilage organisms. Packed in polyethylene drums of 35 kg, 330 kg or 1650 kg net, with tight inner and outer closures; classified as a class-2 inorganic acid corrosive (UN number 93002) and liable to freeze in winter.
