Phosphoric Acid Uses

What are phosphoric acid uses? What is it used for? What is phosphoric acid formula? Given below are the answers to all of these questions and more...


Phosphoric acid is one of the most widely known and used acid. This acid is also known as orthophosphoric acid and is a mineral acid. If you are wondering as to what is phosphoric acid made of, then you need to know that this acid contains three atoms of hydrogen, one atom of phosphorus and four atoms of oxygen. Thus, the formula of phosphoric acid is H3PO4. This is an important acid that has many uses in industrial applications as well as in medicines.

Removal of Rust
One of the most common phosphoric acid uses is to remove rust from surfaces of metals. Phosphoric acid can be used as a rust converter with the help of direct application to rusted iron, or steel tools and other rusted surfaces. The phosphoric acid converts reddish-brown iron, that is, ferric oxide to black colored ferric phosphate. After treatment with phosphoric acid, the black ferric phosphate coating can be scrubbed off, thus, revealing fresh metal surface. However, there may be need for multiple applications of phosphoric acid before all the rust can be removed. The black phosphate coating can be left in place though, so that it provides further corrosion resistance. Rust remover is sometimes a greenish liquid that is suitable for dipping but it is more often formulated as a gel.

Use in Processed Food
Phosphoric acid is used as an additive to acidify foods and beverages like various colas. This use has managed to stir up a controversy regarding the health effects that this may have on the human body. It provides a tangy or a sour taste and being a mass produced chemical, it is available in large quantities easily.

Medical Uses
Another most important use is in medicine and dentistry. Phosphoric acid is used as an ingredient in over-the-counter anti-nausea medications which also happen to contain high levels of sugar, that is, glucose and fructose. In dentistry, this acid is combined with zinc powder to form zinc phosphate, which is used as a temporary dental cement. It is also used in orthodontics as an etching solution so as to clean and roughen the surface of teeth, before the placement of brackets and other dental appliances. This acid is also used in many teeth whitening solutions to eliminate plaque that may be present on the surface of teeth.

Other Uses
Phosphoric acid is used as the electrolyte in phosphoric acid fuel cells. Phosphoric acid is also used as a cleaner by construction trades so as to remove mineral deposits, cementinous smears and hard water stains. Hot phosphoric acid is used in micro-fabrication to etch silicon nitride. Phosphoric acid is used as a flux by hobbyists so as to aid in soldering. Phosphoric acid in also used in hydroponics pH solutions to lower the pH of nutrient solutions. One of the phosphoric acid uses also includes it being used as an electrolyte in copper electro-polishing for burr removal. In compound semiconductor processing, phosphoric acid is a commonly used wet etching agent. Phosphoric acid is used as a pH adjuster in cosmetics and other skin care products. It's also used as a chemical oxidizing agent for activated carbon productions. It is used with distilled water as an electrolyte in oxyhydrogen generators.

This is an important acid that is prepared by different routes. Its application in various industries ranging from metallurgy to the food industry make this a popular acid.