CHEMISTRY SAFETYISSUES
Included in this section:
- Chemical Storage
- Purchase, Use and Disposal of Chemicals
- Special Note: Disposal of Wastes in Sanitary Sewers
- Chemical Spills
- Safety Products in the Chemistry Lab
- Safety in the Chemistry Lab
Chemical Storage
Ideally, one chemical/biological storage room under the supervision of a qualified person is essential for each school. The storage room should have adequate security. Safety facilities should include the following:
. Approved fire extinguishers and containers of sand and soda positioned near an escape route.
. Spill control and clean-up materials.
. Master control shut-off valves for gas, water, and electricity.
. Approved eye/face wash.
. Shower.
. Smoke detector.
. Forced ventilation from floor to ceiling with exhaust above roof level.
. Lip-edged wooden shelving secured to wall with top shelf below eye level.
. A communication system to the main office or emergency center.
The alphabetical method of storing chemicals presents hazards because chemicals which react violently with each other may be stored in close proximity.
Flammables must be stored in a separate flammable cabinet.A separate cabinet is also required for certain acids. Flinn Catalog identifies which acids must be isolated.
Chemicals can be sorted according to the scheme presented in the Flinn Chemical Catalog
Reference Manual.The Flinn Manual suggests sorting the chemicals into ORGANIC and
INORGANIC groupings which are then further sorted into compatible families as suggested below:
INORGANIC ORGANIC
1. Metals, hydrides 1.Acids, anhydrides, peracids
2. Halides, sulfates, sulfites, thiosulfates2.Alcohols, glycols, amines, imines,
3. Amides, nitrates* nitrites*,3.Hydrocarbons, esters, aldehydes nitric acid4.Ethers*, ketones, ketenes,
4. Hydroxides, oxides, silicates, carbonates,halogenated hydrocarbons,carbon carbonethylene oxide
5. Sulfides, selenides, phosphides, carbides,
5.Epoxy compounds, isocyanates nitrides
6.Peroxides,hydroperoxides, azides*
7. Hypochlorites, soln, and hydrogen peroxide7.Sulfur
8. Borates, chromates, manganates,8.Phenols, cresols permanganates
9. Acids (except nitric)
10. Sulfur, phosphorus*, arsenic, phorphorus pentoxide*
* These chemicals deserve special attention due to their potential instability.
Consult the Flinn Chemical Catalog Reference Manual for diagrams of suggested shelf storage patterns for inorganic and organic chemicals.
NOTE: Be sure to follow local fire codes when storing flammable chemicals in separate cabinets.
Purchase, Use and Disposal of Chemicals
It is suggested that the following guidelines be followed when purchasing, using and disposing of chemicals.
. If possible, purchase chemicals in class-size quantities only.
. Label all chemicals accurately with date of receipt or preparation, the initials of the person responsible, and pertinent precautionary information on handling.
. Follow all directions for disposing of residues and unused portions of reagents. (see Flinn Disposal guide.)
. Properly store flammable liquids in small quantities in containers with a provision for bonding and receiving vessels when the liquid is transferred.
. Never open a reagent package until the label has been read and completely understood.
. Read the Material Safety Data Sheet on hand before using a chemical.
In regards to disposing of unwanted or waste chemicals:
Prepare a complete list of chemicals of which you wish to dispose.
. Classify each of the chemicals on the disposal list into a hazardous or non-hazardous waste chemical.
. Unlabeled bottles (a special problem) must be identified to the extent that they can be classified as hazardous or non-hazardous wastes. (Some laboratories will analyze a mystery bottle for a fee.)
. When in doubt concerning the disposal of unwanted or waste chemicals, contact the Office of Environmental Management, Akron Public Schools.
.The Office of Environmental Management will arrange for the disposal of unwanted chemicals twice a year.
Special Note: Disposal of Wastes in Sanitary Sewers
Small quantities of some wastes can be disposed of in sanitary (not storm) sewers. However, this practice is discouraged. The quantities should be limited to a few hundred grams or milliliters, flushing with large quantities of water to achieve high dilution.
Inorganic salts in which both the cation and anion are relatively non-toxic are generally permissible for drain disposal if they are soluble to a degree of a few percent. Check local regulations for possible restrictions. Mineral acids or bases should be neutralized before drain disposal.
Don't throw any unwanted chemicals down the drain or in the wastebasket. Some organic compounds that are reasonably soluble in water are suitable for drain disposal. Again, check local regulations if in doubt. Generally, short chain alcoholsaldehydes, amides, amines, carboxylic acids, esters, ethers, and ketones are suitable. One exception would be low boiling point flammable liquids, such as diethyl ether. Other exceptions include explosives like azides or peroxides.
Chemical Spills
Chemical spills occur in any laboratory. In order to minimize health, property, and fire hazards, the following supplies should be on hand to deal with spills:
. Neutralizing agents, such as sodium carbonate
. Absorbants, such as sand and vermiculite
. Paper towels
. Sponges
. Mop and bucket
. Broom and dust pan
. Rubber gloves
. Safety glasses
. Apron
. Plastic garbage bags
. Mercury sponge
. Seamless polyethylene bottle for mercury spills
If the spill occurs, follow these priorities:
. Attend to any person whose skin or clothing may have been affected.
. Notify others in the room to stay clear of the spill.
. Avoid breathing the vapor if it is a liquid spill. Open windows and/or turn on exhaust fans.
. Evacuate classroom.
. Clean up the spill wearing appropriate protective clothing.
. Seek information on spill management (See Flinn, MSDS, or Emergency Response Guide).
Solid spills of low toxicity materials can be swept up using a broom and dust pan.Place the material in a plastic bag if it is to be placed in a solid waste container. Do not dump it directly into a metal waste can! Dispose of waste according to safe disposal procedures.
If a liquid spill* occurs, wear rubber gloves and use the following procedure:
. For inorganic acids or bases, use a neutralizing agent, such as soda ash. For other materials, use dry sand, vermiculite, or paper towels. (NOTE: Do not use paper towels for concentrated sulfuric acid spills.)
. Carefully clean any splashed liquid from other bottles or apparatus.
. Mop up the spill.
. Dispose of residues according to safe disposal procedures.
* Mercury spills present a special type of hazard due to the acute and chronic toxicity of mercury vapors.
Flinn (1998) makes the following suggestions for cleaning up mercury spills:
.Immediately following a mercury spill or thermometer breakage, provide maximum ventilation by opening doors and windows.
.Never sweep the spill with a broom. Attempt, to the extent possible, to avoid creating free mercury vapor.Avoid contaminating brooms, your shoes, or other items in the area. Put plastic bags over your shoes if you must walk in the spill area.
.Push the pools of mercury together.
.Pick up the pools with a closed device like a medicine dropper. Transfer the picked up droplets to a seamless polyethylene or polypropylene bottle.
Once the visible droplets have been found, picked up, and placed in a seamless plastic bottle, the remaining hidden droplets can be cleaned up in the following manner:
.Zinc metal powder can be spread about the spill area. If the mercury is clean, the zinc and mercury will form a safe amalgam which can be easily collected and disposed of in the same fashion as the elemental mercury.
.Go over the area with a mercury sponge. A mercury sponge contains high surface area zinc fibers. Again, an amalgam will form if the mercury is clean.
.A mercury vacuum cleaner is available from Flinn on a rental basis. Never use a standard vacuum cleaner! This will create a mercury aerosol which will be spewed into the surrounding area.
.It is strongly suggested that mercury thermometers be eliminated for most laboratory use.
Safety Products in the Chemistry Lab
There are several safety products which are essential to the proper operation of a chemistry program.
The following is a brief description of those products which should be included in a safety inventory:
Eye Protection: The State of Ohio requires that each student has personal eye protection. The material should conform to America National Standard Institute (ANSI) Z87.1-1979 standards for use, durability, and cleaning. Appropriate chemical resistant goggles are available through the Akron Public Schools Warehouse. Eye-wash stations should be made available with signs posted in the lab identifying their location. All students should be instructed in the use of the eye-wash stations.Fire Extinguishers: The four standard types of fire extinguishers are
(1) Class A - used for paper and trash,
(2) Class B - used for flammable liquids,
(3) Class C - used for electrical fires, and
(4) Class D - used for flammable metals. The ideal extinguisher is a carbon dioxide or dry powder unit rated for Class A, B and C fires.
Fire extinguishers must be recharged on a regular basis.The chemistry teacher should inspect the condition of the unit at least once per week. Extinguishers are recharged annually. Make sure that the proper unit is returned to the same lab position.
Provide proper instruction on the use of a fire extinguisher to the class prior to the first laboratory exercise at the beginning of each school year.
First Aid: First-aid kits should be available in the lab with the location clearly marked and identified. The instructor should take inventory of the kit on a regular basis. The instructor and the students should be aware of the proper use of the contents of the first-aid kit.
Miscellaneous: There are several other items of safety which a chemistry lab should contain. Among them are an emergency shower, safety signs, safety posters, bottle carriers, storage cans, and labels. It is advisable that the instructor inform the students of the proper use of these items.
Safety in the Chemistry Lab
The Facility:
. Take note of any structural abnormality or unsafe condition in the classroom or storeroom and report it in writing to the appropriate authority.
. Chemistry facilities should be used for chemistry classes only.
Equipment Use:
. Broken glassware is to be disposed of in a container separate from paper and other wastes.
. All rough glass edges should be fire polished.
. Do not have students insert glass tubing. Teachers should do this procedure. When inserting glass tubing into a rubber stopper, lubricate the tubing with glycerine, wrap the tubing with a towel, and gently twist the tubing into the stopper hole.
. Water from sinks should never be turned on to the highest degree. Gentle washing of materials prevents splashing.
. Check charge level of fire extinguishers. Recharge, if necessary. After recharging, make sure that the proper extinguisher is returned to the lab.
. Maintain emergency lighting (e.g., flashlight).
. Maintain a file of instruction/operating manuals for all science equipment.
. Check for stability of glassware support.
Chemicals:
. When transferring a chemical into a secondary container the following information should be included on the label: chemical name, formula, concentration, solvent (if solution), hazard warning, name or initials of person responsible for transfer.
. When performing lab activities involving toxic vapors, flammable gases and noxious odors, use a fume hood.
. Containers of chemicals should be carried with two hands. Never grab a container from the top only.
. Maintain the smallest amount of chemicals needed for individual projects throughout the year.
Teacher Responsibility:
. Do not permit horseplay in the lab. Maintain control.
. Instruct students on the use of all safety equipment in the room.
. Identify the locations of all safety equipment by appropriate signs.
. Group sizes should conform to a number which can perform the experiment safely.
. Plan enough time for the experiment and clean up of materials.
. Develop safety lessons with objectives that can be measured.
. Develop an accident plan.
. Instruct students never to eat or drink in the classroom.
. All gas valves in the lab should be turned off at the end of the lab.The master gas valve - if one exists - should be turned off at the end of the day.
. Chemicals should be stored under lock and key when not in use.
. Students should never be left unsupervised.
. The lab should always be locked when not in use.
. All students performing scientific experiments that involve a hazard to the eye must wear appropriate eye protection. This rule must include visitors.
. Full length aprons or lab coats, which are designed to protect from chemical hazards, must be worn when appropriate.
. Gloves, which are designed to withstand chemical hazards, should be worn when appropriate.
. Chemicals should be stored in approved containers and storage devices.
. Do not smoke in the lab, storage areas, or adjacent office areas.
. Instructors should weigh the educational value of an experiment with the potential risks involved.
. Take a periodic inventory of the lab safety devices and report defective devices to the appropriate authority.
Teacher Responsibility:(continued)
. Take note of any structural abnormality or unsafe condition in the classroom and report it to the appropriate authority.
. Observe students for any abnormal physical or mental activity before, during, or after an experiment. Do not allow any student who displays abnormal physiological characteristics to perform an experiment.
. Develop a plan to secure the lab during emergency drills.
. Potential hazards should be identified prior to an experiment.
. Include a list of safety rules with a substitute's lesson plan. However, it is advisable a substitute monitor a lab activity.
. Document safety violations and report safety concerns in writing to the appropriate authorities.
. Always store chemials with labels in the forward, readable, position.
. Do not use unlabeled chemicals.
. Use a grease pencil for labeling glassware.
. Report missing/stolen materials to the principal immediately.
Student Responsibility:
. Report all accidents to the instructor, no matter the degree.
. Never mix chemicals without a defined procedure.
. Never drink water from any lab glassware.
. Never point the open end of a test tube at yourself or other students.
. Never smell the contents of a test tube unless instructed to do so as a part of the experiment. When so instructed, never bring the container directly to the nose, but wave your hand over it and move the air toward your nose.
. Work areas should be uncluttered and free of combustible materials.
. Never touch any part of your face while working in the lab.
. Never taste a chemical in the lab.
. All students should wash their hands at the end of the experiment.
. Glassware and equipment should not be placed at the edge of a table top or work space.
Student Responsibility (continued)
. Never leave experiments while in progress.
. It is advisable that contact lenses not be worn during an experiment without the teacher's knowledge.
. Long hair should be pulled back and fastened during labs.
. Perform only authorized experiments as assigned by the instructor.
. Inform the instructor of any breakage, spills, or contamination at once.
. Sinks are not to be used to dispose of matches or paper.
. Do not wear jewelry when working in the lab.
. Always read labels/MSDS before handling any chemical.
. If instructions are unclear, ask your instructor for clarification.
Do's and Don'ts:
. Allow falling objects to fall; never try to grab a falling object.
. Allow glassware to cool after heating by placing it on a special surface.Do not submerge hot glassware in water.
. Always pour acid into water. Never pour water into acid.
. Never pipette with your mouth. Use a pipette bulb or an automatic filler.
. Asbestos should never be used in the lab.
. Known carcinogens should never be used in the lab.
. At no time should students be given hazardous chemicals to take home.
. At no time should the teacher accept unsolicited chemicals without approval of administrative personnel. Some agencies use schools as 'dumping grounds' to ridthemselves of liability. This practice can increase the hazards for school personnel and students and increase disposal costs.
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