Question

The reaction of slaked lime with \(\mathrm{Cl}_{2}\) gas gives: (a) A mixture of \(\mathrm{Ca}(\mathrm{OCl})_{2}, \mathrm{Ca}(\mathrm{OH})_{2}, \mathrm{CaCl}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\) (b) Quick lime (c) Baryta water (d) Only \(\mathrm{Ca}(\mathrm{OCl})_{2}\)

Short answer

The correct answer is (a): A mixture of \(\mathrm{Ca(OCl)_2}, \mathrm{Ca(OH)_2}, \mathrm{CaCl_2}\), and \(\mathrm{H_2O}\).

Step-by-step solution

Understanding the Reaction

The chemical reaction given involves slaked lime, which is chemically known as calcium hydroxide (\(\mathrm{Ca(OH)_2}\)), reacting with chlorine gas (\(\mathrm{Cl}_2\)). This is a chlorination reaction of an alkaline hydroxide often used to produce bleaching powder or related compounds.

Chemical Equation Formation

The reaction between calcium hydroxide and chlorine gas can be represented as: \( \mathrm{2Ca(OH)_2 + 2Cl_2 \rightarrow Ca(OCl)_2 + CaCl_2 + 2H_2O} \). This equation shows the formation of calcium hypochlorite \((\mathrm{Ca(OCl)_2})\), calcium chloride \((\mathrm{CaCl_2})\), and water \((\mathrm{H_2O})\).

Identifying the Products

In the reaction, we see that there are three main products formed: - Calcium hypochlorite (\(\mathrm{Ca(OCl)_2}\)) - Calcium chloride (\(\mathrm{CaCl_2}\)) - Water (\(\mathrm{H_2O}\))Additionally, unreacted calcium hydroxide \((\mathrm{Ca(OH)_2})\) might also be present, which fits the description of a mixture containing all these compounds as specified in option (a).

Conclusion

Based on the reaction products and the options given, the correct answer is (a). The reaction forms a mixture of \(\mathrm{Ca(OCl)_2}, \mathrm{Ca(OH)_2}, \mathrm{CaCl_2}\), and \(\mathrm{H_2O}\). This includes all components listed in option (a) but not those in any other option.

Key concepts

Chlorination

Chlorination is a chemical process that involves the addition of chlorine to a substance. This method is commonly used for disinfecting water, making it safe for drinking, and in various chemical reactions to produce different compounds.
In the context of the reaction in question, chlorination involves chlorine gas reacting with calcium hydroxide. This is a specific type of reaction where chlorine replaces one or more of the hydroxyl groups in calcium hydroxide, leading to the formation of useful compounds such as calcium hypochlorite.
There are several benefits to chlorination, such as:

• It effectively kills bacteria and other microorganisms, making water safe for everyday use.
• It prevents the growth of algae and helps in maintaining clear water in swimming pools.
• It is an economical method for large-scale water purification and chemical manufacturing.

Overall, chlorination is a versatile and vital process in both industrial and environmental contexts.

Calcium Hydroxide

Calcium hydroxide, often referred to as slaked lime or hydrated lime, is a chemical compound with the formula \(\mathrm{Ca(OH)_2}\).
This compound is derived from quicklime (calcium oxide) by adding water. It appears as a colorless crystal or white powder and is known for its role in various applications.
Calcium hydroxide is used in building materials, like cement and plaster, due to its ability to harden with time by absorbing carbon dioxide.
In the context of chemical reactions, calcium hydroxide serves as an alkaline substance that easily reacts with gases like chlorine.
Some key properties of calcium hydroxide include:

• It is slightly soluble in water, forming a solution known as limewater.
• It is often used for soil stabilization and as a pH adjuster in agriculture.
• Its alkaline nature makes it suitable for neutralizing acidic solutions in various processes.

Understanding calcium hydroxide's properties helps to elucidate its role and behavior in chemical reactions, such as the one forming a mixture with chlorine.

Calcium Hypochlorite

Calcium hypochlorite is a powerful chemical compound with the formula \(\mathrm{Ca(OCl)_2}\), known for its disinfecting and bleaching properties.
Formed during the chlorination of calcium hydroxide, calcium hypochlorite is a significant ingredient in bleaching powder.
This compound is widely used in water treatment, providing an efficient method for drinking water disinfection and swimming pool maintenance.
Its role and advantages include:

• It acts as a strong oxidizing agent, meaning it can kill bacteria and pathogens effectively.
• It helps in maintaining water hygiene by preventing the growth of algae and bacteria.
• It is relatively stable under normal storage conditions, making it easy to handle and transport.

Moreover, calcium hypochlorite's effectiveness in sanitation contributes greatly to public health by ensuring microbial-free water.

Bleaching Powder

Bleaching powder is a chemical mixture known for its use in sanitation and bleaching applications.
It typically consists of calcium hypochlorite, calcium chloride, and other related compounds.
This powder results from the reaction of slaked lime with chlorine gas, combining the benefits of these chemicals into one convenient form.
Bleaching powder is commonly used for:

• Disinfecting drinking water and wastewater, making them safe for consumption and release.
• Bleaching fabrics and paper, owing to its effective oxidizing ability.
• Acting as a disinfectant in hospitals and household cleaning products, helping to maintain hygienic environments.

Given its versatility and effectiveness, bleaching powder remains a vital chemical product in both domestic and industrial settings, ensuring cleanliness and safety in various applications.