Problem 133 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the following: List-I List-II 1\. Beryl (i) \(\mathrm{KCl} \cdot \mathrm{MgCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}\) 2\. Carnalite (ii) \(\mathrm{MgCO}_{3}\) 3\. Asbestos (iii) \(3 \mathrm{BeO} \cdot \mathrm{Al}_{2} \mathrm{O}_{3} \cdot 6 \mathrm{SiO}_{2}\) 4\. Magnesite (iv) \(\mathrm{Ca}_{2} \mathrm{Mg}_{5} \mathrm{Si}_{8} \mathrm{O}_{22}(\mathrm{OH})_{2}\) (v) \(\mathrm{CaSO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O}\) The correct matching is: \(\begin{array}{llll}1 & 2 & 3 & 4\end{array}\) (a) (iii) (iv) (i) (ii) (b) (iv) (iii) (ii) (i) (c) (iii) (i) (iv) (ii) (d) (iii) (i) (ii) (iv)

Step-by-Step Solution

Answer

The correct match is option (c): 1(iii), 2(i), 3(iv), 4(ii).

Step 1: Match Beryl

The compound Beryl is associated with the chemical formula \(3 \mathrm{BeO} \cdot \mathrm{Al}_{2} \mathrm{O}_{3} \cdot 6 \mathrm{SiO}_{2}\). Therefore, match 1 with (iii).

Step 2: Match Carnalite

Carnalite is identified by the chemical formula \(\mathrm{KCl} \cdot \mathrm{MgCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}\). Therefore, match 2 with (i).

Step 3: Match Asbestos

The mineral Asbestos commonly refers to the formula \(\mathrm{Ca}_{2} \mathrm{Mg}_{5} \mathrm{Si}_{8} \mathrm{O}_{22}(\mathrm{OH})_{2}\). Therefore, match 3 with (iv).

Step 4: Match Magnesite

Magnesite is represented by the chemical formula \(\mathrm{MgCO}_{3}\). Therefore, match 4 with (ii).

Step 5: Verify the Correct Option

Now that we have matched: \(1 \rightarrow (iii), 2 \rightarrow (i), 3 \rightarrow (iv), 4 \rightarrow (ii)\). This combination corresponds to option (c).

Key Concepts

Mineral Identification

Identifying minerals is both an art and a science, requiring an understanding of their physical properties and chemical compositions. Each mineral possesses a unique set of characteristics that can include color, hardness, luster, and density. However, in the context of inorganic chemistry, recognizing minerals often revolves around their specific chemical formulas.

• Beryl: This mineral is known for its hardness and stunning green color in the form of emeralds. Its chemical formula is \(3 \mathrm{BeO} \cdot \mathrm{Al}_{2} \mathrm{O}_{3} \cdot 6 \mathrm{SiO}_{2}\), identifying it as a silicate of beryllium and aluminum.
• Carnalite: Typically found in evaporite mineral deposits, it's recognized by the formula \(\mathrm{KCl} \cdot \mathrm{MgCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}\) and is important for its extraction of potassium and magnesium.
• Asbestos: Referring to a group of fibrous minerals, it's known for heat resistance, commonly represented by \(\mathrm{Ca}_{2} \mathrm{Mg}_{5} \mathrm{Si}_{8} \mathrm{O}_{22}(\mathrm{OH})_{2}\).
• Magnesite: This mineral is a carbonate, noted for its white-to-gray color and is represented by \(\mathrm{MgCO}_{3}\).

Understanding these chemical formulas aids in the process of correctly identifying and utilizing these minerals.

Chemical Formulas

Chemical formulas are the shorthand representation of compounds, conveying their atomic composition and ratios. They are vital for understanding the fundamental nature of materials in inorganic chemistry. Each formula provides a clear picture of how elements combine and what properties the resulting compound may exhibit. Let's delve into a few examples from our exercise:

• \(3 \mathrm{BeO} \cdot \mathrm{Al}_{2} \mathrm{O}_{3} \cdot 6 \mathrm{SiO}_{2}\): This formula illustrates the composition of Beryl, showing a ratio of three beryllium oxides to two aluminum oxides to six silicon dioxides, making it a complex silicate mineral.
• \(\mathrm{KCl} \cdot \mathrm{MgCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}\): Denotes Carnalite, combining potassium chloride and magnesium chloride with a significant water content, forming a hydrated mineral.
• \(\mathrm{Ca}_{2} \mathrm{Mg}_{5} \mathrm{Si}_{8} \mathrm{O}_{22}(\mathrm{OH})_{2}\): Used for Asbestos, this intricate formula highlights the presence of calcium and magnesium as well as complex silicate structures with hydroxide groups.
• \(\mathrm{MgCO}_{3}\): Simple and straightforward, this formula for Magnesite centers around a single magnesium atom bonded with a carbonate group.

Mastering these formulas allows for the identification and classification of minerals, revealing their potential uses in industry and beyond.

Matching Exercises

Matching exercises are a practical tool for reinforcing knowledge and understanding of key concepts in inorganic chemistry. These activities sharpen recognition skills and help students link different pieces of information, such as names of minerals with their chemical formulas.
Here’s why they are effective:

• They foster quick recall skills, encouraging students to memorize by association rather than rote learning.
• By requiring a student to match, these exercises engage critical thinking and analytical skills to discern correct pairings, enhancing memory retention.
• Such exercises incorporate immediate feedback, which is crucial for learning as students can promptly see the results of their thought processes.

In our given problem, each mineral had to be matched with its corresponding chemical formula, such as pairing Beryl with its complex silicate formula. The process solidifies learning through practical application, making the connections clearer and more intuitive.