Preparation of Phosphoric Acid
Phosphoric Acid has many applications and it is generally prepared by the two processes namely:
- Wet process
- Thermal process
Wet Process
In wet process, phosphoric acid is produced from a naturally occurring crystal rock Fluorapatite. This crystal contains the phosphate mineral. Fluorapatite is reacted with concentrated sulphuric acid (H2SO4) and water (H2O). This reaction results in the formation of phosphoric acid and calcium sulfate (gypsum) along with some insoluble impurities. The reaction occuring in wet process is as follows:
Ca5(PO4)3Cl + 5H2SO4 + 10H2O → 3H3PO4 + 5CaSO4·2H2O + HCl
The side products and impurities formed during this reaction can be removed by the process of filtration and evaporation. Then by vacuum distillation this acid is concentrated to ca 56-70% P2O5 (super phosphoric acid). The impure product formed by the wet process can be used as fertilizer manufacture without any further purification.
Thermal Process
Thermal process is another method used to obtain phosphoric acid. This process is helpful in obtaining a purer form of phosphoric acid. In this process,a phosphorus rock along with coke is heated or burnt at high temperature (about 2000 ℃ ) in a furnace in the presence of air. This results in the formation of phosphorus pentoxide which is further condensed to form a white powder. It is then hydrated to obtain phosphoric acid. The reaction occuring in wet process is as follows:
Step 1: Formation of phosphorus pentoxide
P4 + 5O2 → 2P2O5
Step 2: Hydration of phosphorus pentoxide
P2O5 + 3H2O → 2H3PO4
We can also obtain a condensed form of polyphosphoric acids by passing the steam to the burner. The products from the burner are then moved into a hydration tower to obtain phosphoric acid as the gaseous phosphorus oxide is absorbed there. The phosphoric acid obtained by thermal process is more pure ranging from 75 – 80%.
Phosphoric Acid
Phosphoric acid is a colorless, odorless, inorganic compound. It is mainly found as an aqueous solution with a concentration of about 85%. It is represented by the chemical formula H3PO4. It is extensively used in distinct fields. Its applications include its usage in manufacturing fertilizers, various pharmaceutical products, skin care products, and much more.
In this article, we will do an in-depth study of Phosphoric acids, their properties, their usage, and others in detail.
Table of Content
- What is Phosphoric Acid?
- Structure of Phosphoric Acid
- Preparation of Phosphoric Acid
- Types of Phosphoric Acid
- Properties of Phosphoric Acid
- Uses of Phosphoric Acid
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Phosphoric Acid Overview |
|
|---|---|
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IUPAC Name |
Ortho Phosphoric Acid |
|
Chemical Formula |
H3PO4 |
|
Molar Mass |
97.99 g/mol |
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Melting Point |
42.4 °C OR 108.3 °F OR 315.5 K |
|
Boiling Point |
407 °C OR 765 °F OR 680 K |
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