Laboratory and Practical Skills

Laboratory: A chemistry laboratory is where students observe physical and chemical characteristics of substances following definite procedures.

Basic Precautions:

• Conduct yourself responsibly at all times
• Experiments performed in presence of lab instructor
• Check equipment before use
• Determine potential hazards before beginning work
• No crowding in lab - maintain safe distance
• Don't bring any food items in lab
• Never taste or smell any compound or gas directly
• To smell a gas, waft the fumes towards your nose
• Don't pour chemicals down drains
• Acids and bases: neutralize first, then dispose

Explosive Chemicals: Chemicals that cause sudden release of pressure, gas and heat when they experience sudden shock. Examples: Picric acid, 4-dinitrophenyl hydrazine, benzoyl peroxide, nitrocellulose.

Flammable Chemicals: Chemicals with flashpoint around room temperature. Examples: Ethers, methylated spirit, benzene, pentane.

Safety Instructions:

• Obtain prior approval from teacher
• Always use smallest quantity
• Always conduct experiment in fume hood
• Remove all other chemicals around you
• Inform other people
• Always wear safety spectacles, gloves, lab coat
• Keep flammable compounds away from heat source
• Pour flammable liquid very carefully
• Properly dispose off hazardous waste
• Do not store flammable liquid in refrigerator

Corrosive Chemicals: Attack living tissues when in contact. Can be solids, liquids or gases. Attack skin, eyes, respiratory tract, intestine. Examples: Mineral acids (HF), caustic alkalies, acetic acid.

Safety Precautions:

• Use in fume cupboards to avoid breathing corrosive vapours
• While mixing acid with water: always add acid slowly to water, never vice versa
• Ensure eye wash and emergency shower available
• Wash affected area with soap and water, seek medical attention

Toxic Chemicals: Poisonous material capable of causing serious health problems. Examples: Mercury, benzene, chlorine, pesticides, ammonia, hydrogen cyanide.

Safety Precautions:

• Wear gloves, masks, protective devices
• Keep work area well ventilated
• Keep in original container
• Do not work alone
• Wash hands with soap and water after finishing
• Always work in fume hood
• Seek immediate medical aid if exposed

Reactive Chemicals: May cause fires, explosions, evolve dangerous gases. Examples: Calcium hydride, Na, Li, azides, picric acid, AlCl₃, benzoyl peroxide.

Safety: Handle with utmost care, segregate while storage, minimize quantity, use shields and heavy gloves.

Radiation Hazards: High dose damages functioning of tissues and organs. Can cause vomiting, burns, hair loss. Radioactive materials emit alpha, beta, gamma rays causing extreme damage.

Safety: Keep sources shielded, avoid prolonged exposure, stay inside (walls protect), never operate without training, wear protective clothing, monitor exposures using badges.

Asphyxiation Hazards: Gas or vapour causes unconsciousness or death through suffocation. Sufficient oxygen level essential for normal breathing. Examples: Hydrogen cyanide, carbon monoxide, nitrogen, argon, helium, methane, carbon dioxide.

Safety: Store and use in well-ventilated areas, wear lab coat, glasses, gloves, dispose strictly per instructions, if exposed wash with running water and seek medical attention.

Hazard Signs: Proper warning signs posted on hazardous materials, sensitive equipment, and specified areas. Indicate specific precautions must be observed. If you see such signs, be alert and take extra care.

Importance: Ensure everyone entering understands and acts accordingly to maintain laboratory safety.

Personal Protective Equipment (PPE): Should be available to students to face emergency situations. Reduce exposures to hazardous chemicals.

Examples: Lab coat, protective glasses, face shields, apron, boots, hearing protection.

Fire Extinguisher: Chemical laboratories must have portable fire extinguisher. Can quickly control small fire. All students should know location and how to use it. Training session should be held.

Emergency Shower: Facility of shower should be available in lab. Location and working must be told to everybody. Essential in case of fire or other emergency.

Handling Emergency:

• Stay calm, do not panic
• Alert people in area to evacuate
• In case of fire: close doors to confine it, use fire extinguisher
• In case of chemical emergency: adopt safety procedures
• Call and assist emergency staff

Emergency Drills: Periodic drills should be held with compulsory participation. Students should be involved practically to handle emergency situations. Check firefighting and other equipment whether in proper working order.