Problem 153 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is/are oxide ore (s)? (a) Bauxite (b) Cassiterite (c) Haematite (d) Cryolite

Step-by-Step Solution

Answer

The oxide ores are Bauxite, Cassiterite, and Haematite.

Step 1: Understand Oxide Ores

Oxide ores are minerals that contain metals combined with oxygen. They are typically found in higher oxidation states where metals are bonded with oxygen.

Step 2: Examine Each Option

Go through each option to determine if it is an oxide ore: (a) Bauxite is primarily Al₂O₃, making it an oxide ore. (b) Cassiterite is SnO₂, an oxide ore. (c) Haematite is Fe₂O₃, making it an oxide ore. (d) Cryolite is Na₃AlF₆, which is not an oxide ore as it contains fluoride instead of oxide.

Step 3: Identify Correct Options

From the examination, options (a) Bauxite, (b) Cassiterite, and (c) Haematite are oxide ores, while (d) Cryolite is not. Therefore, the choices that are oxide ores are (a), (b), and (c).

Key Concepts

Bauxite

Bauxite is a type of rock primarily composed of aluminum hydroxide minerals like gibbsite, boehmite, and diaspore. Although it's not pure oxide like some other minerals, it is rich in alumina \( (Al_2O_3) \), making it an important source of aluminum, a widely used metal in industries.
Understanding bauxite involves recognizing its role as the chief ore of aluminum production. This ore undergoes several processing steps to extract aluminum, which starts with crushing the bauxite and then refining it to produce alumina.

• Extraction: Bauxite is mined from surface mines, located worldwide in tropical and subtropical zones.
• Processing: It is refined using the Bayer Process to obtain alumina, a white powder.
• Application: Alumina is then electrolyzed to produce metallic aluminum, using the Hall-Héroult process.

Bauxite is essential in various sectors like aerospace, transportation, and construction, underlining its global economic importance.

Cassiterite

Cassiterite is the main ore of tin, with the chemical formula \( SnO_2 \). It is an oxide mineral found in a range of geological environments. Known for its ability to withstand corrosion, tin is vital for manufacturing and industrial applications.

• Occurrence: Cassiterite appears in hydrothermal veins and alluvial deposits. It is found in places like Malaysia, Bolivia, and Southeast Asia.
• Properties: The mineral is characterized by high density and a distinctive crystal structure, which ranges from yellow to brown or black.
• Usage: It's primarily used to produce metallic tin through a reduction reaction process.

Tin derived from cassiterite is extensively used in the production of solder, which is critical in electronics and various coatings to prevent corrosion.

Haematite

Haematite, also spelled hematite, is a substantially common iron oxide with the formula \( Fe_2O_3 \). It is esteemed as the primary ore of iron and exhibits a rich reddish appearance, typical of its appearance and usage.
Haematite plays a crucial role in steel production, contributing over 98% of the world’s iron mining.

• Characteristics: It is often found in sedimentary rocks and is easily identifiable for its metallic luster and red-to-brown coloration.
• Mining Sites: Prominent deposits exist in regions including Brazil, Australia, and Russia.
• Iron Production: The extracted haematite undergoes smelting to derive iron, subsequently used to manufacture steel.
• Other Uses: Beyond its industrial applications, haematite serves in jewelry and pigment formation due to its color and polish.

Its significance cannot be overstated, especially given the demand for iron across all technology and construction industries.