Problem 76 - A Complete Resource Book in Chemistry for JEE Main

Question

The composition of diaspore is (a) \(\mathrm{Al}_{2} \mathrm{O}_{3} \cdot 3 \mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{Al}_{2} \mathrm{O}_{3} \cdot \mathrm{H}_{2} \mathrm{O}\) (c) \(\mathrm{Al}_{2} \mathrm{O}_{3}\) (d) \(\mathrm{Al}_{2} \mathrm{O}_{3} \cdot 2 \hat{\mathrm{H}}_{2} \mathrm{O}\)

Step-by-Step Solution

Answer

The composition of diaspore is (b) \( \mathrm{Al}_{2} \mathrm{O}_{3} \cdot \mathrm{H}_{2} \mathrm{O} \).

Step 1: Identify the mineral formula for diaspore

Diaspore is a naturally occurring mineral that is part of the bauxite family. The known chemical formula for diaspore is \( \mathrm{AlOOH} \), which is often represented in hydrated form.

Step 2: Translate the chemical formula of diaspore

The chemical formula \( \mathrm{AlOOH} \) can also be expressed as \( \mathrm{Al}_{2} \mathrm{O}_{3} \cdot \mathrm{H}_{2} \mathrm{O} \). This represents the relation between aluminium oxide and water in a hydrated form.

Step 3: Match with given options

From the options provided, we identify which one corresponds to \( \mathrm{Al}_{2} \mathrm{O}_{3} \cdot \mathrm{H}_{2} \mathrm{O} \). Option (b) is \( \mathrm{Al}_{2} \mathrm{O}_{3} \cdot \mathrm{H}_{2} \mathrm{O} \), which is the equivalent formula for diaspore.

Key Concepts

Mineral Chemistry

Mineral Chemistry is a field that focuses on the chemical composition and structure of minerals. Each mineral has a unique chemical formula that defines its composition. For example, diaspore is a mineral with the chemical formula \( \mathrm{AlOOH} \). This formula indicates that diaspore is composed of aluminum (\( \mathrm{Al} \)), oxygen (\( \mathrm{O} \)), and hydrogen (\( \mathrm{H} \)). Understanding the precise composition helps in identifying and categorizing minerals.
Mineral chemists use various analytical techniques to determine such compositions. This includes examining how the atoms are arranged within a mineral's structure. Some methods used in mineral chemistry are:

• X-ray diffraction
• Spectroscopy
• Electron microprobe analysis

These techniques provide essential insights into the unique physical and chemical properties of minerals like diaspore.

Hydrated Compounds

Hydrated Compounds are an important concept in chemistry as they contain water molecules within their structure. Diaspore, for instance, is a hydrated compound where the formula \( \mathrm{Al}_{2} \mathrm{O}_{3} \cdot \mathrm{H}_{2} \mathrm{O} \) can be understood as aluminum oxide with one water molecule.
Hydrated compounds are remarkable because their properties change with the presence of water. Some notable features of hydrates include:

• They can form crystal structures.
• The attached water can affect their stability.
• Heating can remove the water, transforming them into anhydrous (water-free) compounds.

Identifying the amount of water in a compound helps chemists understand its reactivity and stability. It is especially relevant in industries, where moisture content can affect material performance.

Bauxite Family

The Bauxite Family consists of different aluminum-containing minerals and is a primary source of aluminum ore. Diaspore, along with gibbsite and boehmite, is part of this mineral family. The term 'bauxite' is used for the general mixture of aluminum-bearing minerals, often including clay minerals and iron oxides.
In industrial applications, bauxite is crucial because it is refined through processes like the Bayer Process to produce pure aluminum oxide. This oxide is then further processed to produce metallic aluminum. Bauxite thus serves as:

• The primary source of aluminum globally.
• A raw material for products ranging from packaging to aerospace components.
• An important mineral in understanding earth's geological and economic aspects.

By studying minerals like diaspore in the bauxite family, scientists and engineers can optimize the extraction and production of aluminum, a metal critical to modern industry.