Problem 83 - A Complete Resource Book in Chemistry for JEE Main

Question

Cinnabar is an ore of (a) \(\mathrm{Cu}\) (b) \(\mathrm{Zn}\) (c) \(\mathrm{Hg}\) (d) \(\mathrm{Pb}\)

Step-by-Step Solution

Answer

Cinnabar is an ore of Mercury (Hg).

Step 1: Understanding the Question

We need to determine which metal cinnabar is an ore of. An ore is a type of rock that contains sufficient minerals with important elements that can be extracted.

Step 2: Recall the Composition of Cinnabar

Cinnabar is a naturally occurring mineral. It is known for its bright red to brownish-red color. The chemical formula of cinnabar is important here. Cinnabar is primarily composed of mercury sulfide, with the chemical formula \( \mathrm{HgS} \).

Step 3: Identify the Element from the Chemical Formula

The formula \( \mathrm{HgS} \) indicates that cinnabar contains mercury (Hg) as a major component. We should match this with the options given in the exercise.

Step 4: Match the Answer with the Given Options

From the options provided:- (a) \( \mathrm{Cu} \) stands for Copper.- (b) \( \mathrm{Zn} \) stands for Zinc.- (c) \( \mathrm{Hg} \) stands for Mercury.- (d) \( \mathrm{Pb} \) stands for Lead.Since cinnabar is \( \mathrm{HgS} \), it is an ore of mercury, represented by \( \mathrm{Hg} \).

Key Concepts

Cinnabar

Cinnabar is a distinctive mineral known for its striking appearance and significant role as an ore. This mineral is easily recognized by its vivid red to brownish-red color, making it both visually appealing and useful in mineral identification. Cinnabar's primary composition consists of mercury sulfide, denoted chemically as \( \mathrm{HgS} \). This indicates that mercury (Hg) is the primary metal extracted from cinnabar. Due to its mercury content, cinnabar has historically been an important resource for obtaining this metal. However, because of mercury's toxicity, handling cinnabar requires precautions to avoid health hazards. Whether found in crystals or massive deposits, cinnabar’s striking color and composition make it an important subject of study in mineralogy.

Mercury Extraction

The process of mercury extraction from cinnabar involves specific techniques to separate the mercury from sulfur. Mercury is typically obtained through the roasting of cinnabar. This process involves heating cinnabar in the presence of air or oxygen, which causes the mercury sulfide (HgS) to decompose into elemental mercury and sulfur dioxide. The chemical reaction can be represented as: \[ \mathrm{HgS} + \mathrm{O}_2 \rightarrow \mathrm{Hg} + \mathrm{SO}_2 \]This roasting process requires controlled conditions to ensure that mercury vapors are safely condensed and collected. The collected mercury is then purified for use in various applications. It's essential to manage the process carefully to minimize environmental and health risks inherent to mercury vapor exposure. In modern times, alternatives and safer practices are being explored due to these risks.

Mineral Identification

Mineral identification is a crucial skill in geology and resource extraction. In the case of cinnabar, the identification involves recognizing its unique color and form, as well as understanding its chemical composition. Minerals have several key characteristics that aid identification, such as:

• Color: Cinnabar's bright red color is a primary identifying feature.
• Streak: The color of the powder left by the mineral when scratched on a surface can help identify it, usually reflecting its natural color.
• Luster: Cinnabar has an earthy to sub-metallic luster, distinguishing it from similar looking substances.
• Density: The high density of cinnabar, due to its mercury content, can be another hint in identification.

Understanding these characteristics helps in distinguishing cinnabar from other minerals, ensuring accurate identification for academic, commercial, or practical purposes.