Difference Between Dicalcium Phosphate and Monocalcium Phosphate

Key Difference – Dicalcium Phosphate vs Monocalcium Phosphate
 

Dicalcium phosphate and monocalcium phosphate are inorganic compounds that are composed of calcium cations and phosphate anions. These compounds have different applications in different industries such as food industry, the pharmaceutical industry, etc. The key difference between Dicalcium phosphate and monocalcium phosphate is that Dicalcium phosphate has a HPO₄^2- anion per molecule whereas monocalcium phosphate contains two H₂PO₄^– anions per molecule.

CONTENTS

1. Overview and Key Difference
2. What is Dicalcium Phosphate
3. What is Monocalcium Phosphate
4. Similarities Between Dicalcium Phosphate and Monocalcium Phosphate
5. Side by Side Comparison – Dicalcium Phosphate vs Monocalcium Phosphate in Tabular Form
6. Summary

What is Dicalcium Phosphate?

Dicalcium Phosphate is calcium phosphate having the chemical formula CaHPO₄ and its dihydrate. The chemical formula of this compound is CaHPO₄. The molar mass of this compound is 136.06 g/mol. It is an odorless compound that appears as a white power. The density of Dicalcium phosphate varies with its hydration. When anhydrous, the density of Dicalcium phosphate is 2.92 g/cm³ whereas the density of its dihydrate forms is 2.31 g/cm³. At higher temperatures, Dicalcium phosphate decomposes instead of melting.

Figure 01: Dicalcium Phosphate Powder

There are three possible chemical structure of Dicalcium phosphate.

1. Dehydrate form (CaHPO₄.2H₂O)
2. Hemihydrate form (CaHPO₄.0.5H₂O)
3. Anhydrous form (CaHPO₄)

The crystal structure of Dicalcium phosphate crystals is triclinic. The IUPAC name of this compound is Calcium hydrogen phosphate dehydrate. The reactants used for the production of Dicalcium phosphate include calcium hydroxide (Ca(OH)₂) and phosphoric acid (H₃PO₄). The production process include the neutralization of calcium hydroxide by phosphoric acid that gives Dicalcium phosphate as a dehydrate precipitate. When its reaction is done at or around 60°C, the anhydrous form is produced.

H₃PO₄ + Ca(OH)₂ → CaHPO₄

The degradation of this final product can form hydroxyapatite. Therefore, in order to avoid the degradation, sodium pyrophosphate is added to the reaction mixture.

Dicalcium phosphate is used in manufacturing cereals, dog treats and noodle products as a dietary supplement. It also has some pharmaceutical applications; used as a tableting agent. Apart from that, Dicalcium phosphate is used as a food additive, and is also found in toothpaste as a polishing agent.

What is Monocalcium Phosphate?

Monocalcium phosphate is a calcium phosphate having the chemical formula Ca(H₂PO₄)₂. It is commonly found as the monohydrate form. The IUPAC name of this compound is Calcium dihydrogen phosphate. The molar mass of this compound is 234.05 g/mol. The melting point of Monocalcium phosphate is 109°C and the boiling point is 203°C. However, at higher temperatures, it decomposes.

Monocalcium phosphate is prepared by using treating calcium hydroxide with phosphoric acid with a high purity. The reaction is as follows.

Ca(OH)₂ + 2 H₃PO₄ → Ca(H₂PO₄)₂ + 2 H₂O

The final product or the Monocalcium phosphate solid tends to convert into Dicalciumphosphate form.

Figure 02: Monocalcium Phosphate Crystals

There are two main applications of Monocalcium phosphate; it is used in fertilizer production and as a leavening agent. Monocalcium phosphate or triple superphosphate is a solid that is used as a fertilizer. It is also used as a leavening agent in food industry.

What are the Similarities Between Dicalcium Phosphate and Monocalcium Phosphate?

• Both Dicalcium Phosphate and Monocalcium Phosphate are composed of phosphate anions.
• Both Dicalcium Phosphate and Monocalcium Phosphate are used in food industry.
• Both Dicalcium Phosphate and Monocalcium Phosphate compounds decompose at high temperatures.
• Both Dicalcium Phosphate and Monocalcium Phosphate compounds are produced from calcium hydroxide and phosphoric acid.

What is the Difference Between Dicalcium Phosphate and Monocalcium Phosphate?

Summary – Dicalcium Phosphate vs Monocalcium Phosphate

Dicalcium phosphate and Monocalcium Phosphate are inorganic compounds that are composed of anions derived from phosphoric acid. The difference between Dicalcium phosphate and monocalcium phosphate is that, Dicalcium phosphate has a HPO₄^2- anion per molecule whereas monocalcium phosphate contains two H₂PO₄^– anions per molecule.

Reference:

1.Hendrickson, Kirstin. “What Is the Purpose of Dicalcium Phosphate?” COM, Leaf Group, 14 Aug. 2017. Available here
2.“Monocalcium phosphate.” Wikipedia, Wikimedia Foundation, 15 Feb. 2018.  Available here
3.“Dicalcium phosphate.” Wikipedia, Wikimedia Foundation, 17 Feb. 2018.  Available here

Image Courtesy:

1.’Dicalcium phosphate’By Chemicalinterest – Own work, (Public Domain) via Commons Wikimedia 
2.’Monocalcium phosphate spoon’By Chemicalinterest at en.wikipedia – Own work (Public Domain) via Commons Wikimedia 

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