Problem 11 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

The one that is not a carbonate ore is: (a) malachite (b) calamine (c) siderite (d) bauxite

Step-by-Step Solution

Answer

Bauxite is not a carbonate ore.

Step 1: Identify Carbonate Ores

First, we need to identify which of the given options are carbonate ores. Carbonate ores are those which contain the carbonate ion \(CO_3^{2-}\).

Step 2: Analyze the Options

Examine each option: (a) Malachite is \(CuCO_3\cdot Cu(OH)_2\), a carbonate ore. (b) Calamine is \(ZnCO_3\), a carbonate ore. (c) Siderite is \(FeCO_3\), another carbonate ore.

Step 3: Identify the Different Ore

The remaining option is (d) Bauxite, which is primarily composed of aluminum hydroxides like \(Al_2O_3 \cdot 2H_2O\), and does not contain any carbonate ions.

Key Concepts

Mineralogy

Mineralogy is the scientific study of minerals — their structure, properties, classification, and the way they form. One important aspect of mineralogy is understanding how minerals are grouped based on their chemical composition and structure.
For example, carbonate ores are classified into a group where mineral components include the carbonate ion \( CO_3^{2-} \). Understanding mineralogy is crucial for identifying ores and determining valuable metals contained within them.
Mineralogists analyze factors such as crystal symmetry, hardness, and cleavage, which can vastly differ between various mineral groups. This helps in distinguishing carbonate minerals from non-carbonate minerals such as bauxite, which primarily contains aluminum compounds.

Chemical Formulas

Chemical formulas represent the elements present in a compound and their proportions. They are critical in identifying whether a particular ore belongs to a specific group like carbonate ores.
For instance, the formula for malachite is \( CuCO_3 \cdot Cu(OH)_2 \); it combines copper carbonate with copper hydroxide, indicating it is part of the carbonate ores. Similarly, calamine (\( ZnCO_3 \)) and siderite (\( FeCO_3 \)) are also carbonate ores.
The formula of bauxite, however, is more complex, typically containing aluminum oxides and hydroxides such as \( Al_2O_3 \cdot 2H_2O \). Bauxite's lack of carbonate ions in its chemical formula classifies it as a non-carbonate ore. Recognizing these formulas allows chemists and geologists to accurately categorize and utilize ores.

Ores Identification

The process of ores identification includes determining the mineral composition and classifying the ores according to their chemical properties. This involves comparing known chemical formulas to see which ions or radicals they contain.
In the context of carbonate ores, identifying these involves checking for the presence of the carbonate ion \( CO_3^{2-} \). The exercise of identifying carbonate ores from a list emphasizes this concept by contrasting them with non-carbonate ore like bauxite.
Reliable identification often requires a combination of eye examination, chemical tests, and advanced instruments like X-ray fluorescence (XRF) for precise results. Improving skills in ore identification enables better resource management and efficient metal extraction, crucial for industrial and economic purposes.