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) \(\mathrm{Al}_{2} \mathrm{O}_{3} \cdot 2 \mathrm{H}_{2} \mathrm{O}\)

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 Composition of Diaspore

Diaspore is an aluminum oxide mineral. It is an important ore of aluminum, primarily composed of aluminum oxide and water molecules but with specific water content.

Step 2: Understand the Water Content in Diaspore

Diaspore is characterized by being a hydrate containing only one water molecule per formula unit. The molecular formula can typically be represented as having one part of water H2O bound to the alumina Al2O3.

Step 3: Recognize the Correct Formula

Based on the typical composition of diaspore and the knowledge that it includes a single water molecule linked with the alumina component, its chemical composition is most accurately expressed as \( \mathrm{Al}_{2} \mathrm{O}_{3} \cdot \mathrm{H}_{2} \mathrm{O} \).

Step 4: Match with Given Options

Among the provided options, (b) corresponds to the correct chemical formula of diaspore, which is \( \mathrm{Al}_{2} \mathrm{O}_{3} \cdot \mathrm{H}_{2} \mathrm{O} \).

Key Concepts

Diaspore Mineral

Diaspore is a naturally occurring mineral that plays a vital role as one of the primary ores of aluminum. This mineral is mainly extracted to furnish aluminum on a commercial scale. It is noted for its distinct composition and properties. Diaspore belongs to the group of hydrated aluminum oxides, meaning that it contains both aluminum oxide and a specific amount of water.Represented chemically, diaspore has the composition of \( \mathrm{Al}_{2} \mathrm{O}_{3} \cdot \mathrm{H}_{2} \mathrm{O} \). It is notable for having only one molecule of water attached to each formula unit, a feature that classifies it specifically under hydrated minerals.An interesting aspect of diaspore is its geological presence. It is typically found in bauxite deposits, often appearing alongside other minerals such as gibbsite and boehmite. These minerals collectively occur as ores from which aluminum is safely and economically extracted.

Chemical Composition

The chemical composition of minerals like diaspore is crucial to understanding their properties and uses. In chemistry, the composition refers to the types and ratios of atoms within the mineral's structure. For diaspore, its composition is defined as \( \mathrm{Al}_{2} \mathrm{O}_{3} \cdot \mathrm{H}_{2} \mathrm{O} \), which signifies the presence of two aluminum atoms, three oxygen atoms, and one water molecule.This specific composition allows diaspore to be classified as a hydrated mineral. The water molecule in its structure is integral, influencing its physical properties such as hardness and density. Moreover, the composition plays a significant role in the mineral's stability and behavior during thermal processes. Upon heating, diaspore can lose its water component, altering its physical state and forming different minerals.

Aluminum Oxide

Aluminum oxide, often found within diaspore and other aluminum ores, is a significant chemical compound with wide-ranging applications. Its chemical formula is \( \mathrm{Al}_{2} \mathrm{O}_{3} \), representing a compound consisting of two aluminum atoms bonded to three oxygen atoms.Aluminum oxide is known for its exceptional hardness and high melting point, making it an ideal component for ceramic materials, abrasives, and as a catalyst in chemical reactions. In the context of diaspore and other minerals, aluminum oxide forms the essential building block of materials that are not only economically valuable but also scientifically fascinating due to their unique structural characteristics.Beyond its presence in minerals like diaspore, aluminum oxide frequently appears in various industries:

• As a refractory material in furnaces.
• In the production of aluminum metal through processes like the Hall-Héroult method.
• In creating synthetic gemstones and insulating layers on semiconductor devices.