[Chemistry Class Notes] on Aluminum Oxide Pdf for Exam

What is the Formula of Aluminum Oxide?

The chemical formula for Aluminum oxide is Al2O3. Being amphoteric, it is used in multiple, industrial, chemical, and commercial applications. Also, it is considered as an indirect additive and, thus, used in food substances, which are further approved by the FDA.

Uses to Aluminum Oxide

Most people, when they hear about Aluminum, they think about the foils that are used to cover cooked dishes. In terms of chemical compound – aluminum oxide, it is not familiar with the previous concept. It is a chemical compound, and the same is ionic in nature. The structure has a metal (aluminum) in it along with non-metal (oxygen). As ionic compounds have occurred between metals and non-metals, it involves the exchange the electrons between both the atoms. The metal atom always promotes electrons, and non-metal form provides an ionic bond. 

When it comes to aluminum, it forms an ion with a charge of +3 and thus, forms an ion with an oxygen atom that always ends in forming an ion with a charge of -2. Now, the overall charge of a compound must end in zero, being neutral and, thus, requires two atoms of aluminum and three atoms of oxygen. This balances the charge, and the make the compound neutral. Therefore, the chemical formula for aluminum oxide is Al2O3.

How is Aluminum Oxide Produced?

Aluminum oxide is produced through the Bayer process. It is a process where bauxite is refined to form alumina. The process starts with drying and washing crushed bauxite that contains 30 – 55% of Al₂O₃. The crushed bauxite is formed into slurry by dissolving in caustic soda. Heated temperature is applied that ranges from 230 – 520 degrees Fahrenheit (110 -270 degrees Centigrade). Forming the mixture, it contains a residue called red mud impurities. These impurities are then flittered to come up with an alumina solution. This solution is chemically known as aluminum hydroxide, which is then transferred to a precipitator tank. This tank helps in the cooling and seeding process. The precipitation process allows the seeds to stimulate and forms solid and crystalized aluminum hydroxide. The aluminum hydroxide that settles at the bottom of the tank is then removed. The caustic soda that remains in the mixture is washed properly through several filtration processes. The final stage includes heating the mixture to completely remove any existence of water. It is then passed through a cooling process to form fine white powder in the form of aluminum oxide.