Chemical Reactivity of Phosphoric Acid with Water

Phosphoric acid (H₃PO₄), also referred as orthophosphoric acid, is perhaps the most important phosphorus oxygen acid and is used to make phosphate salts for fertilisers. It’s also used in the production of dental cements, albumin derivatives, and the sugar and textile industries. It’s used as an acidic, fruity flavouring in meals.

Phosphoric acid is a crystalline solid having a melting point of 42.35° C (108.2° F) and a colourless syrupy liquid with a melting point of 42.35° C (108.2° F) in low concentrated form. White phosphorus is used to manufacture higher-grade acid, while phosphate rock is used to make crude acid.

Phosphoric acid

Phosphorus is a necessary plant nutrient that is absorbed by plant roots in the form of the dihydrogen phosphate ion, H₂PO₄–, which is generated from phosphoric acid, H₃PO₄. The availability of phosphoric acid is critical for the production of fertilisers that correct phosphorus deficits in soils.

When Phosphoric acid is react with water then we get

H₃PO₄ +H₂ O ↔ H₃O+ + H₂PO₄–

Uses of Phosphoric acid

Phosphoric acid is used to generate fertilisers in around 90% of the world’s production. It’s mostly broken down into three phosphate salts that are utilised as fertilisers. The three types of phosphates are TSP (triple superphosphate), DAP (diammonium hydrogen phosphate), and MADP (monoammonium dihydrogen phosphate) (MAP).

Phosphates are also utilised in a range of different products, such as soft drinks and as a supplement in cattle, pigs, and poultry feed.

Although their usage as detergent builders has been phased out in many nations, the acid still has a significant purpose in others.

Physical properties of phosphoric acid H₃PO₄

• Phosphoric acid (H₃PO₄) is a white crystalline substance in its pure state.
• Phosphoric acid (H₃PO₄) has a melting point of 42.4°C.
• H₃PO₄ is non-volatile, colourless, and odourless
• It is viscous in liquid form and has a density of 2.030 gcm-3.
• In comparison to other acids, it is a non-toxic acid.

Chemical Properties of Phosphoric acid (H₃PO₄)

• Three H+ ions can be released by phosphoric acid H₃PO₄ . As a result, H₃PO₄ reacts differently than other mineral acids.
• When phosphoric acid (H₃PO₄ ) is treated with a base, three distinct salts are generated.
• In poly-phosphoric and meta-phosphoric acids, dimers or long polymeric chains form when phosphoric acid molecules are heated to high temperatures.

Preparation of Phosphoric Acid H₃PO₄

The following are two commonly used phosphoric acid production methods:

• ‘Wet’ Process:

Phosphoric acid is made from phosphate minerals in fluorapatite (a naturally occurring crystal rock). Concentrated sulphuric acid and water react with fluorapatite. As a result, phosphoric acid (H₃PO₄) and calcium sulphate, as well as other contaminants, are formed. The excess chemical compounds and contaminants are removed using the filtration and evaporation processes. Despite the impure nature of the end product, it can be used to manufacture fertiliser without being cleansed. The reaction is as follows:

Ca₅(PO₄)₃Cl+5H₂SO₄+10H₂O →3H₃PO₄+5CaSO₄.2H₂O+HCl

Thermal Process:

Phosphorus is heated at a high temperature with air in this procedure. Phosphorous pentoxide is formed, which is then condensed into a white powder. The white powder is then hydrated in a separate process to produce phosphoric acid. A purer version of phosphoric acid can be made using this procedure.

Uses of Phosphoric Acid (H₃PO₄)

• In Agriculture:

The agricultural industry is perhaps the most well-known application of phosphoric acid. It’s widely used in the production of manure and as a flavouring agent in chicken feed.

• Pharmaceutical Application:

It’s also used in dentistry, where dental professionals use it as a scratching arrangement and to clean teeth. Phosphoric acid is also found in mouthwashes and toothpastes. Phosphoric acid, on the other hand, is contained in anti-nausea medications.

• Treatment of Rust:

Phosphoric acid is used to dissolve rust and remove it from metal items. In addition, it is utilised to build a coating on the metal’s surface. This helps to keep erosion at bay.

• Skincare Products:

Phosphoric acid is most commonly used in skincare products to change or manage the pH level. It’s also found in toothpaste and cleaning products.

Phosphoric Acid Hazards

At low quantities, phosphoric acid is non-poisonous and does not harm the skin or any other part of the body. It’s dangerous even at larger doses, as it can irritate the skin and even injure the eyes. If vapours from H₃PO₄ are breathed in, it can also disrupt the respiratory system. As a result, this acid should be stored in a metallic or covered fibreboard compartment (with a polyethene internal bundle) and kept cool and well aired.

Conclusion

The page contains all of the critical information that a student needs to know about the Phosphoric acid with water at a basic level, such as its types, uses, physical and chemical properties, among other things. This is a vital piece of equipment for taking Phosphoric acid with water.