Question Video: Describing the Reaction Involved in the Extraction of Aluminum Chemistry

Video Transcript

Fill in the blank. In the extraction of aluminum, the aluminum blank are blank because they blank electrons. (A) Atoms, oxidized, lose. (B) Atoms, reduced, lose. (C) Ions, oxidized, gain. (D) Ions, reduced, lose. (E) Ions, reduced, gain.

To answer this question, let’s look at how aluminum is extracted.

Aluminum is found in an ore named bauxite. Bauxite is made up of a large amount of aluminum oxide with other metal oxides. First, the aluminum oxide, which is called alumina, once it is purified is extracted from the other metal oxides using the Bayer process. Alumina has a very high melting point, making it challenging to work with. However, the aluminum metal can be separated from the alumina. This is done by reducing the aluminum using electrolysis in the Hall–Héroult process.

Since each answer choice has “oxidized” or “reduced,” let us discuss these words in terms of electrons. Oxidation is a chemical reaction where a chemical species loses electrons. And reduction is a chemical reaction where a chemical species gains electrons.

In alumina, Al2O3, the aluminum ions have a three-plus charge. They start as ions, since they are in an ionic compound. Then, the aluminum ions are reduced when each ion gains three electrons to form atoms of aluminum metal. This can be seen in the following half equation. Al3+ plus three electrons yields to produce aluminum.

Filling in the blanks in the sentence, we can see that the correct answer is (E). In the extraction of aluminum, the aluminum ions are reduced because they gain electrons.