Question

Two of the most heavily utilized metals are aluminum and iron. What are the most important natural sources of these elements? In what oxidation state is each metal found in nature?

Short answer

The most important natural sources of aluminum and iron are bauxite and hematite/magnetite, respectively. In bauxite, aluminum is found in the +3 oxidation state, while in hematite, iron is found in the +3 oxidation state, and in magnetite, iron is found in both +2 and +3 oxidation states.

Step-by-step solution

Identify the most important natural sources of aluminum and iron

The most important natural source of aluminum is bauxite, whereas the most important natural source of iron is hematite and magnetite.

Describe the ores of aluminum and iron

Bauxite is a sedimentary rock that is rich in aluminum-bearing minerals, such as gibbsite, boehmite, and diaspore. It is the primary source from which aluminum is extracted and is formed in tropical and subtropical regions through the weathering of rocks containing aluminum silicates. Hematite (\(Fe_2O_3\)) and magnetite (\(Fe_3O_4\)) are iron-based minerals which are commonly found in rocks and soils. Hematite is a reddish-brown mineral and magnetite is a black mineral. Both of these ores are a primary source for iron extraction and production.

Determine the oxidation states of aluminum and iron in their ores

In bauxite, the aluminum-bearing minerals like gibbsite, boehmite, and diaspore all have aluminum in the +3 oxidation state. So, in its natural sources, aluminum is found in the +3 oxidation state. For iron, its oxidation state depends on the mineral it is found in. In hematite, iron has an oxidation state of +3, whereas in magnetite, iron occurs in both +2 and +3 oxidation states. So, in its natural sources, iron is found in both +2 and +3 oxidation states.

Key concepts

Natural Sources

When it comes to meeting the industrial demands for metals, knowing their natural sources is crucial. The natural sources are the places where these metals are most abundantly found and they are extracted for use. Aluminum and iron, two of the most widely used metals, are found in specific types of ores that serve as their primary natural sources.
Aluminum is mainly extracted from a type of sedimentary rock called bauxite. This rock is abundant in minerals like gibbsite, boehmite, and diaspore, which all contain significant amounts of aluminum.
Iron, on the other hand, is primarily sourced from minerals such as hematite and magnetite. These are iron-rich minerals commonly located in rocks and soil and are heavily mined for iron extraction.

• Bauxite: Main source for aluminum, contains aluminum-bearing minerals.
• Hematite and Magnetite: Key sources for iron extraction, found in nature in abundance.

Understanding these natural sources helps in the efficient recovery and utilization of these metals for various industrial applications.

Oxidation States

Oxidation states give us insight into the chemical state and reactivity of elements in their natural environment. This is especially important for metals, like aluminum and iron, as their oxidation states influence extraction processes and final product properties.

In nature, aluminum primarily exists in a +3 oxidation state. This is the stable state found in its primary ore, bauxite, in the form of minerals like gibbsite, boehmite, and diaspore.
Iron, however, demonstrates more variability in its oxidation states. In hematite, iron is found in a +3 oxidation state. In magnetite, iron exists in both +2 and +3 oxidation states, which makes this mineral magnetic and useful in different applications.

• Aluminum: Stable in +3 oxidation state
• Iron: Observed in both +2 and +3 oxidation states, depending on the mineral

These oxidation states are particularly crucial when understanding how these metals are purified for use in various industries.

Aluminum Ores

Aluminum ores are important for producing one of the most utilized metals globally. Bauxite is the principal ore used for the extraction of aluminum. It isn't just a single mineral but a combination of several mineral sources of aluminum.

Bauxite forms through the weathering and breakdown of rocks containing aluminum silicates, often found in tropical and subtropical regions. The main minerals composing bauxite are:

• Gibbsite: (Al(OH)_3unctions as a hydrated aluminum oxide.
• Boehmite: (γ-AlO(OH) represents a polymorph with a different crystalline structure.
• Diaspore: (α-AlO(OH) which is another form of aluminum oxide with different crystalline properties.

Primarily, bauxite serves as the key raw material in the production of aluminum due to these rich aluminum-bearing minerals.

Iron Ores

The essential ores for iron production are hematite and magnetite, both of which are rich in iron and facilitate its extraction and use.

Hematite ( (Fe_2O_3) ) is known as a reddish-brown mineral and is a vital source of iron. It is straightforward to identify through its color and serves as a major iron extraction ore.

Magnetite ( (Fe_3O_4) ) stands out because of its magnetic properties. This black mineral is also a significant source for obtaining iron. It is unique in that it contains both +2 and +3 oxidation states of iron, making it a valuable resource for magnetic applications.

• Hematite: Reddish-brown, main ore with iron in +3 state
• Magnetite: Black, magnetic, with iron in both +2 and +3 states

These ores are pivotal to the iron industry, serving as the backbone for everything from construction steel to various machinery parts.