Problem 86 - A Complete Resource Book in Chemistry for JEE Main

Question

In the presence of cobalt chloride \(\left(\mathrm{CoCl}_{2}\right.\) ), bleaching powder decomposes to form (a) \(\mathrm{Cl}_{2} \mathrm{O}\) and \(\mathrm{CaO}\) (b) \(\mathrm{CaCO}_{3}\) and \(\mathrm{O}_{3}\) (c) \(\mathrm{CaCl}_{2}\) and \(\mathrm{O}_{2}\) (d) \(\mathrm{ClO}_{2}\) and \(\mathrm{CaO}\)

Step-by-Step Solution

Answer

The correct decomposition products are \(\mathrm{CaCl}_{2}\) and \(\mathrm{O}_{2}\), so the answer is (c).

Step 1: Understanding the Problem

We need to determine the chemical reaction products when bleaching powder decomposes in the presence of cobalt chloride, \(\mathrm{CoCl}_{2}\). The choices given are different pairs of chemical compounds, and only one correctly represents the decomposition.

Step 2: Chemical Composition of Bleaching Powder

Bleaching powder is chemically calcium hypochlorite, indicated by the formula \(\mathrm{Ca(OCl)}_{2}\). In the presence of cobalt chloride, it decomposes through a chemical reaction.

Step 3: Analyzing the Decomposition Reaction

In the decomposition reaction, bleaching powder \(\mathrm{Ca(OCl)}_{2}\) decomposes to form calcium chloride \(\mathrm{CaCl}_{2}\) and oxygen \(\mathrm{O}_{2}\) when in contact with \(\mathrm{CoCl}_{2}\). This is a known reaction where cobalt chloride acts as a catalyst assisting in releasing oxygen gas.

Step 4: Identifying the Correct Products

Given the decomposition reaction of bleaching powder, the correct products are \(\mathrm{CaCl}_{2}\) and \(\mathrm{O}_{2}\). This corresponds to option (c) in the problem.

Key Concepts

Decomposition Reaction

A decomposition reaction occurs when a single compound breaks down into simpler substances. In chemistry, this type of reaction is common when a compound reacts to form two or more products. Decomposition reactions can be observed in various scenarios, such as the breakdown of metallic carbonates, chlorates, or other complex molecules. Decomposition reactions are generally endothermic processes, meaning they require energy to proceed. Heat, light, or electricity can supply the needed energy to initiate the reaction. When applied to calcium hypochlorite, or bleaching powder, decomposition results in the formation of calcium chloride and oxygen under specific conditions. Understanding decomposition reactions is crucial, as they are fundamental in changes that substances undergo in chemical processes. They provide insights into the chemical nature of materials and their stability.

Catalysis in Chemistry

Catalysis is a fascinating phenomenon in chemistry, where the rate of a chemical reaction is increased by adding a substance known as a catalyst. Catalysts function by lowering the activation energy needed for the reaction to proceed. While they enhance the reaction, they are not consumed in the process, allowing them to be used repeatedly. In the discussed reaction, cobalt chloride (\(\mathrm{CoCl}_{2}\)) serves as the catalyst. Its presence facilitates the decomposition of calcium hypochlorite into calcium chloride and oxygen.

• Effect of Catalysts: Catalysts offer alternative reaction pathways with lower energy barriers, enabling reactions to occur more quickly and efficiently.
• Types of Catalysts: There are homogeneous catalysts, which are in the same phase as the reactants, and heterogeneous catalysts, which are in a different phase.
• Reusability: Since catalysts are not used up in the reaction, they can be recovered and reused multiple times.

Catalysis is pivotal in both industrial and biological processes, making reactions feasible under milder conditions. Understanding its role aids in developing efficient and cost-effective chemical processes.

Inorganic Chemistry

Inorganic chemistry is the branch of chemistry concerned with the properties and behaviors of inorganic compounds. This includes minerals, metals, and non-metallic elements. Unlike organic chemistry, which studies carbon-containing compounds, inorganic chemistry focuses mainly on substances without carbon-hydrogen bonds. In the scenario of cobalt chloride helping in the decomposition of bleaching powder, inorganic chemistry plays a key role.

• Inorganic Compounds: These include salts like \(\mathrm{Ca(OCl)}_{2}\) and \(\mathrm{CoCl}_{2}\), which participate in various reactions.
• Role of Metals: Transition metals such as cobalt are often used as catalysts in inorganic reactions due to their ability to change oxidation states and form coordination complexes.
• Application: Inorganic reactions and compounds are crucial in countless applications, from pharmaceuticals to agriculture and manufacturing.

Learning inorganic chemistry provides a comprehensive understanding of the diverse and essential compounds that exist in nature and their practical uses in everyday life.