The chemistry laboratory includes hazards and risks. Work in the lab can involve the use of corrosive and toxic chemicals, flammable solvents, and equipment that can cause injury. Whether taking a lab course or working on a research project, students are expected to be familiar with and conscientiously abide by these established safety practices and procedures.
This section is based on the American Chemical Society publications Safety for Introductory Chemistry Students (2010) and Safety in Academic Chemistry Laboratories (2003).
Safety Procedures & Guidelines
Safety is the first concern and the collective responsibility of everyone in the chemistry lab. Accidents most often result from an indifferent attitude, not using common sense, and/or a failure to follow instructions that leads to mistakes. Be sure you know and follow the safety precautions that will protect you and others from harm:
- Familiarize yourself with the hazards of the chemicals and apparatus you are using.
- Read and follow all instructions carefully. When in doubt about a procedure, ask your instructor.
- Maintain an attentive attitude. The lab experience should be enjoyable but serious, with no playing around or using distracting electronic devices.
- Know where to find and how to use all emergency equipment such as fire extinguishers, safety showers, and eyewash fountains. Report any use of equipment to your instructor.
- Never work alone in or remove chemicals from the lab
- Never perform independent experiments, deviate from the experimental plan, or leave an unattended "experiment in progress "without the specific approval of your instructor.
- Keep chemicals and apparatus well away from the edges of lab bench, fume hood, or other workspace.
- Use fume hoods for all operations in which toxic, corrosive, irritating, or flammable chemicals are involved. Be certain that the hood is operating properly and never put your face inside the lab hood.
- Wipe up quickly all chemical spills and bottle rings.
- If chemicals are spilled on skin or clothing, get to shower immediately to wash off with large amounts of cool water, ignoring common courtesies and any possible embarrassment.
- Always treat lab glassware as if it is fragile and check it regularly for chips, breaks, or obvious flaws.
- Allow time for glass to cool before touching it and be cautious when inserting or removing glass tubing from a stopper (use lubricant and a towel) in order to avoid burns and serious cuts.
- Suction flasks may explode under vacuum if they are cracked or weakened. Do not tap flasks under vacuum.
- Sweep up broken glass with a brush and dustpan or piece of cardboard. Absorbent cotton held by tongs works well for cleaning up tiny pieces of glass. A towel should not be used.
- Do not use flammable materials near a flame, potential electrical spark (from switches or motors), or exposed heating element.
- Keep solvent container lids closed whenever possible to prevent escaping vapors.
- In the event of fire or explosion, leave the area immediately to appraise the situation. Determine what action you need to take in order to ensure the safety of yourself and others. Try to put out the fire or stop its spread, but call 911 if this cannot be done within a couple minutes.
- When assembling apparatus, be sure that all control valves or switches are accessible, without reaching through the assembly, in event of a fire.
- Do not inhale the gases from a fire or explosion.
- If your clothing catches fire, do not run. Use the safety shower, wrap yourself in a fire blanket, or roll on the floor to extinguish the flames.
- Be familiar with type, location, and operation of the nearest fire extinguisher. Approach the fire closely and aim the discharge at the base of the fire. Dry chemical fire extinguishers are recommended for flammable liquids and electrical fires. Never use water on electrical fires. Very small laboratory fires may be put out by smothering with a damp towel, dry soda ash, or sand. Report the use of any fire extinguisher to the instructor.
- Wear eye protection (chemical safety goggles!) in the lab at all times, whether working or just watching. Contact lenses worn with goggles are acceptable, but normal prescription eyeglasses do not provide adequate protection. Increase the degree of protection by using face shields, lab hoods, etc. when hazards increase. Students who disregard this rule may be asked to leave the lab.
- Do not prepare or store food or beverages, nor eat, drink, use tobacco products, or apply cosmetics in the lab.
- Avoid inhaling chemical vapors or gases.
- Never pipet by mouth! Use a pipet aid or suction bulb.
- Wear clothing that protects from accidental spills and splashes and that easily can be removed in case of accident.
- Tie back long hair and remove jewelry before entering the lab.
- Wear sensible shoes that cover your feet.
- Wear gloves, lab coats, and lab aprons when appropriate. Remove these before leaving the lab to avoid unintentional transfer of chemicals to other surfaces. Wash your hands with soap and warm water even after wearing gloves.
- Before leaving the lab, be sure that your own work area and the common areas are at least as clean and organized as when you began.
- Dispose of broken glassware in proper receptacles right after breakage.
- Keep lab benches free of spilled chemicals.
- Avoid physical hazards by keeping drawers and cabinets closed.
- Prevent tripping and contamination hazards--never place materials on the floor.
- Always clean glassware before returning it to storage.
Follow your instructor's directions for disposal of chemicals. If you don't know, ask! Improper disposal can result in personal hazard and/or environmental contamination.
Chemical Health Hazards
Any substance can be harmful to living things. Therefore proper caution must be used when handling all substances, especially those encountered in a chemistry laboratory.
There are four main routes by which hazardous materials enter the body:
- Absorption through the lungs via inhalation. This can result in severe harm!
- Absorption through the digestive tract, possibly by eating in a contaminated work area.
- Absorption through the skin.
- Injection through the skin. This can occur through misuse of sharp materials or through contact with wounds or broken skin.
Toxic effects can vary from mild and reversible to serious and irreversible:
- Acute poisoning can be caused by rapid absorption, usually of a single, large, sudden exposure.
- Chronic poisoning occurs by prolonged or repeated exposure but symptoms may not be immediately apparent.
- Cumulative poisons tend to build up in the body by chronic exposures but, again, the effects may not be seen until a critical amount is present.
- Synergistic poisons are two or more hazardous materials which together have a much greater effect than expected from each substance alone.
Chemical Reactivity Hazards
Certain types of compounds react with each other to produce heat, gases, and hazardous products, for example:
- Oxidizing agents react with reducing agents. [Organic tissue has reducing properties.]
- Acids react with bases. Both are corrosive. The heat of reaction usually causes a more severe hazard.
- Substances may react with water, including water vapor in the air.
- Substances may react with oxygen in air.
When handling chemicals:
- Keep your hands away from your face, eyes, and body until after they have been washed thoroughly.
- If you spill any chemical onto your skin, wash it away with plenty of fresh water.
- Do not taste any chemical.
- To sample the odor of a chemical, fan some vapor toward your nose with your hand, and sniff cautiously.
- Do not pipet anything by mouth.
- When diluting acids, pour the acid into the water, slowly and with agitation. Never pour water into sulfuric acid. Instead, carefully add the acid to the water.
- When pouring from a bottle, hold the stopper so that it is not contaminated by foreign substances. Wash any chemicals from the outside of the bottle before returning it to its storage place. Do not return unused chemicals to stock bottles.
- Mercury and its vapor are poisonous. Notify the instructor immediately in case of any spill, (such as a thermometer breakage). Do not pour mercury into the sink drain.
Chemical container labels usually give information about the toxic, flammable, corrosive, and reactive properties and potential hazards of the chemicals they contain. It is imperative to read and heed the label. Not all hazards, however, may be covered on the label.
A Material Safety Data Sheet (MSDS) for each chemical is on file in our stockroom. This information is available for students to consult, but it can be voluminous and technical. The meaning of some words used to describe health hazards in MSDS follows:
||The general rule for all chemicals, even if they are considered non-hazardous.
||Substances that are suspected or known to cause cancer.
||Living tissue as well as equipment is destroyed on contact with these substances.
||Substances that have or may have harmful effects, but have no available literature.
||Substances that irritate skin, eyes, respiratory tract, etc. Nearly all solutions are potential irritants. The effect ranges from mild and temporary to severe and lasting. It is best to avoid as much contact as possible in all instances.
||Substances that cause eye irritation, burning, and tears. Avoid all contact.
||Hazardous when breathed, swallowed, or upon contact with the skin. In sufficient quantity, will lead to death.
||Substances that are hazardous if breathed, swallowed, or upon contact with the skin. Serious health problems may result from short or chronic exposure.