Meta Description
Learn about chlorinated lime (calcium hypochlorite), its preparation, properties, medicinal uses, and safety precautions. Discover how it is used in wound care, water purification, and sanitation.
Introduction
Chlorinated lime, also known as bleaching powder or calcium hypochlorite (Ca(OCl)₂), is a powerful disinfectant, antiseptic, and bleaching agent. It is widely used in water purification, wound disinfection, and sanitation. Due to its strong oxidizing and antimicrobial properties, chlorinated lime is effective against bacteria, viruses, fungi, and algae.
This article explores the preparation, properties, medicinal uses, and safety precautions of chlorinated lime.
Preparation of Chlorinated Lime
Chlorinated lime is prepared by passing chlorine gas (Cl₂) over slaked lime (Ca(OH)₂) in a controlled environment.
Chemical Reaction
This reaction forms calcium hypochlorite (Ca(OCl)₂), calcium chloride (CaCl₂), and water as by-products.
Purification and Storage
- — The final product is a white powder with a strong chlorine odor.
- – It is stored in airtight containers to prevent moisture absorption and decomposition.
Properties of Chlorinated Lime
Chemical Formula: Ca(OCl)₂
Molecular Weight: 142.98 g/mol
Appearance: White or pale-yellow powder
Odor: Strong chlorine-like smell
Solubility: Partially soluble in water (forms hypochlorous acid, HOCl)
pH: Alkaline in solution
Stability: Decomposes when exposed to air or moisture, releasing chlorine gas
Oxidizing Ability: Strong oxidizer, effective in disinfection and bleaching
Assay of Chlorinated Lime
The assay of chlorinated lime is performed to determine the available chlorine content, which is essential for its effectiveness as a disinfectant and bleaching agent. The assay is based on iodometric titration, where the chlorine present in chlorinated lime reacts with potassium iodide (KI) to liberate iodine, which is then titrated with sodium thiosulfate (Na₂S₂O₃).
Reagents Required:
- Sodium thiosulfate solution (0.1 N)
- Potassium iodide (10%) solution
- Dilute acetic acid or hydrochloric acid
- Starch indicator solution
Procedure:
- 1. Weigh accurately about 2 g of chlorinated lime and dissolve in 100 mL of distilled water.
- 2. Filter the solution to remove insoluble impurities.
- 3. Take 25 mL of the clear filtrate in a conical flask.
- 4. Add 10 mL of 10% potassium iodide solution and acidify with dilute acetic acid.
- Chlorine reacts with KI, liberating iodine:
- Titrate the liberated iodine with 0.1 N sodium thiosulfate using a starch indicator until the blue color disappears.
- Repeat the titration for accuracy and note the volume of sodium thiosulfate used.
Calculation:
The percentage of available chlorine is calculated using the formula: \text{Available Chlorine (%) } = \frac{V \times N \times 35.45 \times 100}{W \times 1000}
Where:
- V = Volume of sodium thiosulfate used (mL)
- N = Normality of sodium thiosulfate (0.1 N)
- W = Weight of chlorinated lime sample (g)
- 35.45 = Atomic weight of chlorine
Medicinal Uses of Chlorinated Lime
1. Wound Disinfection (Dakin’s Solution): Diluted chlorinated lime (Dakin’s solution) is used to clean wounds, cuts, and ulcers, preventing bacterial infections. It was historically used in World War I to treat infected wounds.
2. Water Purification and Disinfection: Used to disinfect drinking water, swimming pools, and sewage systems by killing harmful microorganisms. Low concentrations (4–5 mg/L) effectively remove bacteria, viruses, and algae.
3. Antiseptic and Sanitizer: Used in hospitals, food industries, and household cleaning to disinfect surfaces and prevent contamination. Effective against Staphylococcus, Salmonella, and E. coli bacteria.
4. Deodorizing Agent: Neutralizes bad odors caused by bacterial growth and organic decay. Used in toilets, hospitals, and garbage disposal areas.
5. Antifungal and Antimicrobial Agent: Used to treat fungal infections such as athlete’s foot and ringworm by inhibiting fungal growth.
Other Applications of Chlorinated Lime
- – Textile and Paper Industry: Used as a bleaching agent in cotton, linen, and paper production.
- – Food Industry: Used for sterilizing food processing equipment.
- – Chemical Industry: Used in chlorine production and wastewater treatment.
- – Agriculture: Used to disinfect animal shelters and prevent livestock infections.
Side Effects and Precautions
While chlorinated lime is effective, improper handling or excessive exposure can cause:
- 1. Skin and Eye Irritation: Direct contact can cause redness, burns, and eye damage.
- 2. Respiratory Issues: Inhalation of chlorine fumes can cause coughing, throat irritation, and lung damage.
- 3. Toxicity if Swallowed: Ingestion can cause nausea, vomiting, and severe poisoning.
- 4. Environmental Harm: High concentrations can damage aquatic life and ecosystems.
Precaution: Always use diluted solutions for medical or household purposes, wear gloves and protective eyewear, and store in a dry, sealed container.
Conclusion
Chlorinated lime (Ca(OCl)₂) is a powerful disinfectant and antiseptic widely used in wound care, water purification, and sanitation. Its ability to kill bacteria, viruses, and fungi makes it an essential public health and hygiene agent. However, proper handling and dilution are crucial to prevent skin irritation, respiratory issues, and environmental harm.
Frequently Asked Questions (FAQs)
1. Can chlorinated lime be used on wounds?
Answer: Yes, diluted solutions (Dakin’s solution) are used for wound disinfection and infection prevention.
2. Is chlorinated lime safe for drinking water?
Answer: Yes, in small controlled doses (4–5 mg/L), it disinfects drinking water by killing bacteria and viruses.
3. What happens if chlorinated lime is inhaled?
Answer: Inhalation of chlorine fumes can cause respiratory irritation, coughing, and lung damage. Use it in well-ventilated areas.
4. How does chlorinated lime disinfect water?
Answer: It releases hypochlorous acid (HOCl), which kills bacteria, viruses, and other pathogens by disrupting their cell membranes and enzymes.
5. Is chlorinated lime harmful to the environment?
Answer: Yes, high concentrations can pollute water sources and harm aquatic life. Always dispose of it responsibly.
