Learn essential laboratory safety measures for handling hazardous chemicals, preventing accidents, and responding to emergencies. Explore tips, precautions, and detailed procedures to ensure a safe working environment.
(i) Safety in the chemistry laboratory is:
- Correct Answer: (d) a shared responsibility
- Explanation: Safety in a chemistry lab requires all parties—students, professors, and lab in-charges—to collaborate and follow proper safety protocols. It ensures mutual accountability and reduces the risk of accidents.
- Tip: Always assume collective responsibility for safety in shared environments.
(ii) Accidents often result from:
- Correct Answer: (d) all of the above
- Explanation: Accidents are typically caused by a combination of mistakes, lack of common sense, and failure to follow instructions. Awareness and adherence to guidelines can prevent most mishaps.
- Tip: Develop the habit of reading instructions thoroughly and staying alert in practical environments.
(iii) The label “Warning” on a chemical bottle signifies:
- Correct Answer: (c) that the user should be careful when using the chemical
- Explanation: A “Warning” label indicates a moderate level of hazard, requiring careful handling to avoid harm. It is less severe than “Danger” but still demands caution.
- Tip: Familiarize yourself with standard chemical hazard labels (e.g., Warning, Danger, Caution) and their meanings.
(iv) The label “Corrosive” on a chemical bottle indicates:
- Correct Answer: (c) that the contact destroys living tissue
- Explanation: Corrosive substances can cause severe damage to skin, eyes, and other tissues upon contact. Proper handling, including wearing gloves and protective equipment, is essential.
- Tip: Always use personal protective equipment (PPE) when handling corrosive chemicals.
(v) Example of a highly toxic chemical:
- Correct Answer: (c) Potassium Cyanide
- Explanation: Potassium cyanide is highly toxic and can be fatal even in small amounts. Ethanol, acetic acid, and potassium permanganate are not as acutely toxic.
- Tip: Recognize high-risk chemicals and understand their toxicity levels to handle them appropriately.
(vi) Example of self-reactive chemical:
- Correct Answer: (c) Picric acid
- Explanation: Picric acid is a self-reactive chemical that can become explosive under certain conditions. Phenol, potassium, and n-Hexane do not exhibit self-reactive behavior.
- Tip: Store self-reactive chemicals under recommended conditions to prevent accidents.
(vii) When diluting an acid with water:
- Correct Answer: (c) always add acid to water
- Explanation: Adding water to acid can cause a violent reaction, leading to splattering and potential burns. To dilute acid safely, always add the acid slowly to water while stirring.
- Tip: Remember the phrase “AAA”—Always Add Acid (to water).
(viii) What should you do in case of a fire drill in the lab?
- Correct Answer: (c) close gas valves and turn off all equipment
- Explanation: During a fire drill, ensuring that all sources of potential hazards (like gas and electrical equipment) are secured helps prevent accidents and ensures safety.
- Tip: Follow the lab’s fire evacuation protocol and stay calm during drills.
Short Answer Questions:
- Name some corrosive chemicals.
- Examples: Hydrochloric acid (HCl), Sulfuric acid (H₂SO₄), Sodium hydroxide (NaOH).
- What type of safety precautions are adopted to avoid damage due to explosive chemicals?
- Use small quantities.
- Store them in cool, dry conditions.
- Avoid friction, heat, and impact near explosive chemicals.
- What type of damages can reactive chemicals cause?
- Reactive chemicals can cause explosions, fires, toxic gas release, or damage to equipment and surroundings.
- Indicate two such safety instructions that are required to avoid radiation.
- Wear lead aprons or shields.
- Limit exposure time and maintain a safe distance from the radiation source.
- Which chemicals can cause suffocation?
- Examples: Carbon monoxide (CO), Hydrogen sulfide (H₂S), Chlorine gas (Cl₂).
- Why are signs and symbols posted on lab and chemical bottles?
- To alert users of potential hazards.
- To ensure proper handling, storage, and disposal of chemicals.
- How should fire caused by chemicals be handled?
- Use appropriate fire extinguishers (e.g., CO₂ for electrical fires, Class D for metal fires).
- Avoid using water if it reacts with the chemical.
- Why are emergency drills important to face emergency situations?
- They prepare individuals to respond effectively in real emergencies.
- They reduce panic and ensure timely evacuation or intervention.
3. Constructed Response Questions
i. How will you handle an emergency situation caused by fire due to short-circuiting?
- Response:
- Turn off the main power supply: Immediately cut off the electricity to stop the source of the short-circuiting.
- Activate fire alarm: Alert everyone in the vicinity of the fire.
- Use appropriate fire extinguishers: For electrical fires, use a Class C or CO₂ extinguisher. Do not use water as it conducts electricity.
- Evacuate the area: Ensure all individuals leave the premises in an orderly fashion.
- Call emergency services: Contact fire services and provide details about the fire and the lab layout.
- Contain the fire if safe: Close doors to prevent the spread of smoke or fire but ensure personal safety.
ii. What type of reactions should be carried out in a fume cupboard?
- Response:
- Volatile Reactions: Reactions that release harmful vapors, such as ammonia or chlorine gas.
- Toxic Reactions: Processes involving toxic chemicals like hydrogen sulfide or formaldehyde.
- Combustible Reactions: Reactions producing flammable gases or involving volatile solvents.
- Highly Reactive Chemicals: Reactions involving exothermic processes or potentially explosive compounds.
iii. Put forward at least two suggestions to improve safety in the lab.
- Response:
- Implement regular safety training: Educate lab personnel and students on handling chemicals, equipment, and emergency situations.
- Upgrade safety equipment: Ensure fire extinguishers, first-aid kits, and personal protective equipment (PPE) are easily accessible and regularly maintained.
iv. Can you identify warning symbols posted for radiation and asphyxiant chemicals?
- Response:
- Radiation Symbol: A trefoil symbol with three curved blades radiating from a central circle, typically yellow and black.
- Asphyxiant Symbol: There isn’t a universal asphyxiant symbol, but gases like nitrogen and carbon dioxide are often marked with hazard symbols indicating gas under pressure or health hazard.
v. Why do sudden shocks cause some chemicals to explode?
- Response:
Sudden shocks or impacts can destabilize unstable chemical bonds in reactive substances, such as explosives (e.g., TNT, nitroglycerin). This causes rapid decomposition, releasing a large amount of energy in the form of heat, light, and pressure waves, leading to an explosion.
4. Descriptive Questions
i. Explain hazards due to explosive and toxic chemicals.
- Response:
Explosive chemicals can cause significant physical damage, injuries, and even fatalities due to high-pressure shockwaves, flying debris, and heat. Toxic chemicals pose risks such as poisoning, respiratory issues, skin burns, and long-term health effects like organ damage or cancer.
ii. Write down five common safety instructions used to avoid all types of hazards.
- Response:
- Always wear appropriate PPE, including gloves, goggles, and lab coats.
- Never eat or drink in the laboratory.
- Store chemicals in labeled containers and according to their hazard class.
- Dispose of waste according to environmental regulations.
- Familiarize yourself with the location and usage of safety equipment, such as fire extinguishers and eyewash stations.
iii. Explain the importance of warning signs and symbols to avoid any accident in the lab.
- Response:
Warning signs and symbols communicate vital safety information at a glance. They alert users to potential hazards, such as flammable materials, toxic gases, corrosive substances, or radiation. This helps in preventing accidents by guiding proper handling and storage.
iv. Name some toxic chemicals. Describe the effects of spreading toxic gas in the lab.
- Response:
Examples of toxic chemicals include chlorine gas, ammonia, carbon monoxide, and hydrogen cyanide. If a toxic gas spreads in the lab, it can cause respiratory distress, poisoning, and even death. It may also contaminate surfaces and equipment, leading to long-term risks.
v. A student has spilled over a corrosive and explosive chemical due to an accident. Which emergency measures will you take to tackle the situation?
- Response:
- Evacuate the area: Ensure everyone moves to a safe distance.
- Wear appropriate PPE: Protect yourself before addressing the spill.
- Neutralize the spill: Use neutralizing agents recommended for the chemical (e.g., sodium bicarbonate for acids).
- Ventilate the area: Turn on fume hoods and exhaust systems to disperse fumes.
- Contact emergency services: Inform the lab supervisor and hazardous material response team.
5. Investigative Question
i. A tanker carrying poisonous chlorine gas leaked, causing an accident in Lahore. Provide proposals to avoid such accidents in the future.
- Response:
- Regular Maintenance: Conduct frequent inspections and maintenance of transport vehicles.
- Training: Train drivers and staff in handling hazardous materials and responding to emergencies.
- Route Planning: Use low-population density routes for transporting toxic chemicals.
- Monitoring Systems: Install gas leak detectors and tracking systems on tankers.
- Emergency Response Protocols: Establish well-equipped response teams and evacuation plans for areas along the route.
