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Phosphoric Acid

Last updated: August 13, 2018

What Does Phosphoric Acid Mean?

This is a weak, colorless, odorless and inorganic acid, commonly known as an accumulation of orthophosphoric acid molecules, H3O4P. In chemistry, it is known as an agent that can bind divalent cations. It is used as a cleaning and roughening agent in medicinal practices; it is used as an acidifying and pH controlling agent. At ambient conditions, it is in solid form, so above 108°F (42.35°C) it is usually 85% an aqueous solution. In the industry, it can be used in the manufacturing of surface finishing agents (paints and coatings) and as a corrosion inhibitor.


Corrosionpedia Explains Phosphoric Acid

This crystalline solid consists of a bonding and of hydrogen, oxygen and phosphor elements in its structure; hence, it has a very good solubility rate in water. It is corrosive to ferrous metals and alloys, and decomposes when exposed to high temperatures (415°F / 213°C). It forms toxic fumes when it is in contact with other organic compounds like alcohol.

Food-grade phosphoric acid is widely used in food products, such as for the fruit-like flavoring of sodas. The acid is linked to proneness to bone fractures and complications in the kidney. The replacement of hydrogen atoms in its structure forms salts. The different types of phosphoric acid come from a rock (crude acid) and white phosphorous if purity is required. It can be made by the hydration of phosphorus oxides.

Due to its aggressiveness (depends on the range of impurities) when wet, it is thus used as a chemical-cleaning agent for stainless steels. Its acidic reactions show up at elevated temperatures: it can attack gold and platinum at these temperatures. It slows the growth of microorganisms such as mold and bacteria.


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