Phosphoric acid is considered a weak triprotic acid. It is a weak acid because it only partially ionizes in solution and since it requires three steps to reach complete ionization it is termed triprotic. Being it is an acid, it also has some other common characteristics with other acids. All acids conduct electricity when in solution because ions can move freely. Phosphoric acid will also react with blue litmus paper turning it red since it has a pH of one even at low concentrations (a 1% aqueous solution has a pH of less than 1).
Phosphoric acid applied in certain reactions involving other materials, produces certain products. Phosphoric acid when combined with a base (neutralization reaction) will react violently and produce water, salt and heat (heat of neutralization). Phosphoric acid in contact with common metals reacts to produce flammable and potentially explosive hydrogen gas. Always use caution when reacting other materials and phosphoric acid.
- Agriculture: Fertilizer and mineral supplements are areas of direct application of phosphoric acid.
- Chemical: Phosphoric acid is used to manufacture phosphate salts and as a catalyst to speed up the setting action of some resins.
- Food: Phosphoric acid is used directly in soft drinks, jams and jellies as an acidity controlling agent, to maintain clarity, for flavor enhancement and to increase the preservative effect. It is also utilized in sugar refining and pet foods.
- Industrial Maintenance: Phosphoric acid assist in applications requiring the descaling of boilers and heat exchanger tubes.
- Metal Finishing: Phosphoric acid is used in metal cleaning and chemical polishing applications.
- Refractories: Phosphoric acid proved to be a strong bonding agent for alumina, carbon, magnesia, and zirconia refractories.
- Sanitizing: Phosphoric acid is an important component of some CIP cleaners that are utilized for cleaning hard and sometimes impossible to reach places.
- Waste Treatment: Phosphoric acid provides nutrients in secondary waste biological treatment processes.