Rule
Never work alone — work in the presence of teachers and laboratory staff, and check that the apparatus is in proper working order before starting.
Do not eat, drink, taste or directly smell anything in the laboratory. If a gas must be smelled, waft its vapours towards you with your hand.
Follow the warning signs, and do not throw used chemicals down the drain — put them in the container meant for them. Acids and bases are neutralised before being washed away.
Safety in the laboratory is a shared responsibility of students, teachers and laboratory staff.
Definition
Explosive chemicals: suddenly release gas and heat under pressure — picric acid, dinitrophenyl hydrazine, benzoyl peroxide, nitrocellulose. A sudden jolt (shock) can set them off, so a closed container of such a chemical must not be shaken.
Flammable chemicals: have a flash point near room temperature — ethers, methylated spirit, benzene, acetone, petrol. Keep them away from flames and never store them in a refrigerator.
Corrosive chemicals: destroy the cells of skin, eyes, the breathing tract and the food pipe — concentrated acids including hydrogen fluoride (HF), bases, glacial acetic acid.
Toxic chemicals: cause serious harm to health — mercury, benzene, chlorine, pesticides, ammonia, hydrogen cyanide gas.
Definition
Reactive chemicals: can cause fires, explosions and the release of dangerous gases if used carelessly — calcium hydride (), sodium, lithium, azides, picric acid, aluminium chloride (), benzoyl peroxide. Store them apart from other chemicals and use the smallest amount possible.
Radiation hazards: long exposure damages muscles and organs, burns the skin and causes hair loss and vomiting. Alpha and beta emitters are very dangerous if breathed in or taken into the body; gamma rays affect the body from outside.
Asphyxiation hazards: gases that lower the amount of oxygen in the air or stop the body using it — hydrogen cyanide, carbon monoxide, nitrogen, argon, helium, methane, carbon dioxide. The victim often does not realise that oxygen has fallen.
Remember
To dilute a concentrated acid, always add the acid slowly to water — never pour water into the acid. So much heat is released that water added to acid can boil and splash the acid out.
Rule
Take your teacher's permission before using a hazardous chemical, use only a small amount, and tell the people working near you.
Work with corrosive, toxic and fuming chemicals in a fume cupboard, and keep the room well ventilated.
If a chemical gets on your body, wash the part at once with soap and plenty of water; move a person who has breathed in a harmful gas into open air and call trained people.
Wash your hands well with soap after finishing work, and dispose of every hazardous material in the prescribed way.
Definition
Warning signs are fixed in the laboratory and on bottles of hazardous chemicals — flammable, explosive, corrosive, toxic, radiation, risk of asphyxiation. A warning sign tells the user to be alert and take the stated precautions before using the chemical.
Personal protective equipment (PPE): lab coat, safety goggles, face shield, gloves, apron, closed shoes and ear protection. It protects the body from splashes, fumes and fire.
Rule
Every student should know where the fire extinguishers and the safety shower are, and how they are used. Emergency drills give this practice before a real emergency happens.
In an emergency: stay calm and do not spread panic; ask people to leave the affected place; in case of fire close the doors so that it does not spread, turn off the gas valves and equipment, and try to control the fire with an extinguisher; inform the emergency staff and help them.
Quick Recap
- ●Never work alone; no eating, tasting or direct smelling; dispose of chemicals in the proper container
- ●Hazards: explosive, flammable, corrosive, toxic, reactive, radiation, asphyxiation
- ●Always add acid to water, never water to acid
- ●Use a fume cupboard for harmful vapours; wear PPE — lab coat, goggles, gloves, shield
- ●Know the warning signs, the location of fire extinguishers and the safety shower, and the emergency steps
