Problem 38 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following ore contains both calcium and magncsium? (a) lime stone (b) dolomite (c) epsom salt (d) carnalite

Step-by-Step Solution

Answer

Dolomite contains both calcium and magnesium.

Step 1: Understand the components of each ore

Identify the chemical composition of each compound. Lime stone is primarily composed of calcium carbonate: \( \text{CaCO}_3 \). Dolomite is composed of calcium magnesium carbonate: \( \text{CaMg(CO}_3)_2 \). Epsom salt is made of magnesium sulfate heptahydrate: \( \text{MgSO}_4 \cdot 7\text{H}_2\text{O} \). Carnalite is composed of potassium magnesium chloride: \( \text{KMgCl}_3 \cdot 6\text{H}_2\text{O} \).

Step 2: Identify ores with both calcium and magnesium

From the compositions identified in Step 1, determine which ore contains both calcium and magnesium. Dolomite \( \text{CaMg(CO}_3)_2 \) contains both calcium (Ca) and magnesium (Mg).

Step 3: Verify other options

Ensure no other option besides dolomite contains both calcium and magnesium. Lime stone contains only calcium. Epsom salt contains only magnesium. Carnalite contains potassium and magnesium, but no calcium.

Key Concepts

Ore Composition

Ores are naturally occurring solid materials from which a metal or valuable mineral can be extracted profitably. Understanding ore composition is essential for identifying the elements present and determining its possible uses and extraction methods. Each type of ore has a unique chemical make-up, giving it distinct properties and applications.
For example:

• Limestone: Contains primarily calcium carbonate, expressed as \( \text{CaCO}_3 \).
• Dolomite: Made up of calcium magnesium carbonate, with the chemical formula \( \text{CaMg(CO}_3)_2 \).
• Epsom Salt: Consists of magnesium sulfate heptahydrate, noted as \( \text{MgSO}_4 \cdot 7\text{H}_2\text{O} \).
• Carnalite: Contains potassium magnesium chloride, represented by \( \text{KMgCl}_3 \cdot 6\text{H}_2\text{O} \).

Recognizing these compositions helps identify which elements are present, such as calcium, magnesium, or others, and informs which ore should be used for specific industrial purposes, like cement production or magnesium extraction.

Calcium Carbonate

Calcium Carbonate is a chemical compound with the formula \( \text{CaCO}_3 \). It is a common substance found in rocks as the minerals like limestone and marble. It is an essential component in the formation of marine organisms' shells and certain snails and eggs.
Calcium carbonate is extensively used in various industries:

• Construction: Used as a building material and as an ingredient of cement.
• Agriculture: Adjusts soil pH levels, providing a source of calcium for plants.
• Manufacturing: Utilized in making glass, paper, and plastics.

This compound plays a crucial role in everyday life, not just to humans but also to the environment, contributing to the carbon cycle. Being oxides of metals, calcium carbonate can be refined further for producing calcium oxide (lime), an important chemical in industrial processes.

Magnesium Compounds

Magnesium compounds are found in many natural ores and have diverse industrial and biological significance. These compounds include magnesium sulfate, magnesium carbonate, and more. Each compound has different uses based on its properties.
Some common magnesium compounds are:

• Magnesium sulfate (Epsom salt): Known for its application in medicine and agriculture, helping in the treatment of muscle soreness and as a fertilizer additive.
• Magnesium carbonate: Used in firefighting, gymnastic chalk, and as an antacid.
• Magnesium chloride (Carnalite component): Processed for producing magnesium metal and chemical synthesis.

Magnesium is a light metal and is a vital element for all living cells. In its compound forms, it supports numerous health benefits and is integral in various industrial applications, from construction to manufacturing. Understanding these compounds allows for the proper utilization of magnesium in technology, health, and environmental sustainability.