Aluminium Phosphate: Overview, Questions, Preparation

Aluminium phosphate is an inorganic salt made by treating the aluminium salts to alkaline conditions, resulting in the formation of Aluminium phosphate. The chemical formula of Aluminium phosphate is AlPO4. Since Aluminium phosphate has piezoelectric qualities, it is used to manufacture various electrical and electronic devices.

Let us look at some of the physical properties of Aluminium phosphate:

1. The molecular weight of Aluminium phosphate is 121.953 g/mol.
2. The density of Aluminium phosphate is 2.56 g/cm3.
3. The melting point of Aluminium phosphate is 1800 0C or 3270 0F, and it decomposes at boiling point.
4. The refractive index is 1.546.
5. It has two covalently bonded units and four hydrogen bond acceptors.
6. Aluminium phosphate does not dissolve in water. It is highly corrosive to metals and tissue.
7. When in liquid form it is a colourless liquid and has an unpleasant odour.
8. Aluminium phosphate has piezoelectric properties.
9. The topological polar surface area of Aluminium phosphate is 86.2 Ų.

Let us now look at some of the chemical properties of Aluminium phosphate:

1. When Aluminium phosphate chemically reacts with magnesium chloride (MgCl2), it forms aluminium trichloride along with magnesium phosphate, which finds its use in some medicines.

2AlPO4 + 3MgCl2 → Mg3(PO4)2 + 2AlCl3

2. When Aluminium phosphate is chemically reacted with hydrochloric acid (HCl), it forms Aluminium trichloride, which is the main working behind curing acidity in our stomach.

AlPO4 + 3HCl → AlCl3 + H3PO4

Aluminium phosphate has many uses. Let us look at some of its uses:

1. It is used in various medicines. Blood pressure medicine uses some amount of Aluminium phosphate in it.
2. As mentioned above in the chemical properties, it is even used to treat acidity in the stomach. It is even safe to use during pregnancy as well.
3. Aluminium phosphate is used in various vaccinations as efficiency enhancers.
4. Aluminium phosphate finds its use in preparing dental cement, metal coatings, refractory binders, and glaze compositions.
5. Aluminium phosphate is also used as a white colourant for dental cement, corrosion inhibitors, and pigments.
6. Aluminium phosphate is also used in the manufacture of cement and adhesives.
7. It is used to manufacture different kinds of oils like refined oil products, fuel oils, drilling oils, etc.
8. It is also used in the manufacturing of various chemicals for laboratories.
9. Aluminium phosphate finds its use in the plastic industry as well in the manufacturing of plastic additives. 
10. Aluminium phosphate is used in various toner and printer inks.

The details regarding aluminium phosphate and various compounds in the same family can be studied under the chapter ‘Acids, Bases, and Salts’.Besides it, you would get to know about their chemical properties and the reactions with different compounds.

There is a mention about Aluminium and phosphate in the chapter ‘The S-block elements.’ The uses of phosphate in various items have been described.

1. Which of the following medicines is used for treating indigestion in the stomach?

(a) Analgesic (b) Antiseptic (c) Antibiotic (d) Antacid

Answer: (d)

2. Write complete balanced word equations for the reaction.

a. Aluminium powder reacted with dilute sulphuric acid

b. Iron filings with dilute hydrochloric acid

Answer: (a)- 2Al + 3H2SO4 — Al2(SO4)3 + 3H2 

               (b)- Fe + 6HCl — 2FeCl3 + 3H2

3. A milkman adds a small amount of baking soda to fresh milk. Why does he shift the pH of the fresh milk from 6 to alkaline level?

Answer: Fresh milk can get sour quickly because of the presence of lactic acid and so by adding baking soda, the pH level deflects towards the alkaline side which in turn saves the milk from getting sour.

Q: What is the chemical formula of aluminium phosphate?

Q: What is the molecular weight of aluminium phosphate?

Q: What is the melting point of aluminium phosphate?

Q: State one chemical property of aluminium phosphate?

Q: What are some of the uses of aluminium phosphate?