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MIRIAM C. NAGEL Awn High School Avon. CT 06001
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Chemical Storage Miriam C. Nagel Avan High School Avon. CT 06001
The safety of chemical storage in a high school lab requires a different perspective from that of a university or research lah. The ~ r o h l e m sare not unique, hut the emphasis is different. secondary schools offer only general chemistry, although usuallv there are courses for different levels of ability. ~ e a d acces; ; to a variety of chemicals in relatively small amounts is essential. Inevitably, lab periods are too short and too rushed. I t is common for different classes and different teachers to share the same facilities and to have as few as three minutes to exchange places. Secondary teachers are usually involved with many different students and see them in different contexts. leavine teachers with little time to maintain their chemical storage &as. Rarely, if ever, is one person paid exclusivelv to manaee the stockroom. Facilities ior chemical >tor.lge in high sihooli :Ire st4doin i k l t d . Little rhuurht miiv have been giwn ro .~siurinra.liemird Too often, it is a safety when thestockroom was multipurpose room, used for prep as well as storage. Teachers' desks, files, and other furniture are sometimes placed there. On occasion. the room is used (unwiselv so) for students working on independent projects. Generally, the physical layout of the chemical storage area is beyond the jurisdiction of the teacher, hut responsibility for safety in the area is shared with the school administration. Security for chemicals in secondary schools is critical. Adolescents are often too adventurous and precocious. Safety and security in high schools is considerably more complex than just installing a sturdy door with a strong lock, though that dare not he overlooked. The number of different persons needing access to the area and the short intervals availahle between classes to swap supplies make maintaining a locked room difficult. Administrative and custodial demands often require the use of common kevs which. inevitahlv, " . reduce securitv. Given the constrain& of limited space and time for maintenance. it is essential that all chemicals have a definite d a c e in the stockroom and that they be kept in that place. All containers should he k e ~ well t closed. There should he no pervasive odor when the room or a cabinet door is opened. I t is i m ~ o r t a n to t reassess the storage . area during the annual chemicals inventory: Are all the stored chemicals in secure, properly labeled and dated containers? Are chemicals all stored at safe heights on uncrowded shelves? Are incompatible chemicals ~hysicallyseparated to prevent accidental miuinor7
shelves and disposed of properly? Are emergency cleanup supplies for spills ready for use? Is the,fweextinguisher in place? Has it been checked recently? Do you know how to use it? At the secondary level, i t is no simple task to arrange the variety of chemicals needed in a typical stockroom so that all the conditions for safe storage are met. What "should he" and what "is" are not always reconcilable. When the best possible location (under existing conditions) is determined for each
156
Journal of Chemical Education
chemical, enter the shelf number on the Inventory Card for the oarticular chemical, as noted in the recent Safety Tips featire on "Inventory Controls." The safe height for a chemical container is one that can he reached easily. Store large and/or heavy containers on low shelves. Do not place containers above the top shelf or on cabinet tops. Space containers so that the hurried teacher can readily take a needed chemical without disturbing other containers. When putting away new stock, move the oldest container to the front so it will he used first. If the temperature and humidity of the stockroom are not reasonably uniform, it may be unwise to store some chemicals over the summer. Like many schools, one suburban high school is located in an open field. The chemistry lab and stockroom are located just under a poorly insulated, flat roof. One year during a prolonged August heat wave, the storeroom got so hot the plastic cap on a partially filled 7 lh bottle of nitric acid cracked. Yellow-red fumes filled the air space in the hottle. On another tier of shelves, amakeshift glass container of calcium oxide cracked, probably due to the heat and humidity, and spewed calcium oxide on everything around and below it. Fortunately, there was little direct contact between the acid fumes and oxide, but the painted steel shelves still show the damage. Alerted by the mishap, the administration belatedly installed air conditioning in the stockroom. In ,t,mt. ixilitir,, tht, task r,i segrrg;~tin:: incompatible c.ht:micals ,.an In n \.1rtua1jipaw p11nI1..For ~pecit'iclists of
similar publications. Once the lists have been studied, the teacher in charge of storage will have to evaluate the space availahle, and then plan how to place the strong oxidizing aeents a safe distance from organic solids, etc. The Flinn "Ehemical Catalog Reference ~ a n u a l ""provides a top-tobottom shelf arrangement plan which may he helpful. Besides segregation frim their incompatibles, certain chemicals require extra care in storage. Mercury should he stored in tightly sealed polyethylene bottles. As with all chemicals, store the smallest practical amount. Sodium must he kept under kerosene. The container should then he set in a larger - can or heavy crock containing vermiculite or sand and sodium carbonate. (Vermiculite can sometimes be accumulated from shipping - - cartons.) Potassium tends t o form peroxides. anv~ lessons the secondarv level that iustifv . ~ Are - there - ~ ~ at~ the risk of a peroxihe explosion? Before orkering chekcafs that nose exnlosion hazards. studv their characteristics and ~
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comprehensive article like David A. Pipitone's "Safe Storage of chemical^."^ It might also he well to read up on liability! Chlorine water and bromine water need not he purchased
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Mallinckrodt Chemical Wor!is. P.O. Box 5439. St. Louis. MO 63160 V. Steere or in "Safety in the chemical ~aboratory,'' Vol. 2, (Editor),The Division of Chemical Education of the ACS, Easton, PA 18042, 1971, p. 108. MCB ManufacturingChemists, inc., 480 Democrat Road. Gibbstown, NJ 08027. National Fire Protection Association. 470 Atlantic Ave , Boston, MA 02210. Fiinn Scientific, Inc., P.O. Box 231, Batavia, IL 60510. Pipitone. David A,, The Science Teacher, 16. (February 1981).
orm man
or stored for qualitative work at the high school level. They can easilv as needed-the chlorine water from "he nrenared . acidifying dilute 'household sodium hypochlorite bleach. Do this under t h e hood. The hromine water can he nrenared from . . oxidizing a bromide solution with the chlorine water. Compressed gases require special care in storage. Unless absolutely required by a special curriculum, it is unwise to purchase compressed gases for secondary schools. Caps must he securely in place if cylinders are stored, and the cylinders stored away from all possible exposure to heat, chemical corrosion, and random blows. They should be stored in a secure upright or horizontal position. Excellent detailed information on the use and care of compressed gas cylinders will he found on pages 26 and 27 of the third edition (1979) of "Safety in Academic Chemistrv Laboratories." Quantities of flammable and combustible liquids should be restricted in storage to the smallest practical supply. They should he stored with care in approved containers and cabinets under guidelines set forth in NFPA Standards No. 30 "Flammable and Combustible Liquids Code" and No. 45 "Fire Protection for Laboratories Using Chemicals." Every seasoned secondary teacher knows that the unexnected is a definite nossibilitv. Under the harried conditions imposed by tight schedules and the multipurpose uses of many stockrooms, adequate preparations should be made to clean u~ spills. Cleanup supplies are available commercially for every contingency, or they can be improvised. They should
include neutralizing agents, sodium carbonate and sodium bisulfate, and absorbents such as sand and clay ("Kitty LittePn). Sponges and towels should not be used to clean u p spilled oxidizers. A receptacle for cleaned-up spills must be inert chemically, be fireproof, and have a secure lid. "Cease fire" waste receptacles are also available commercially. Stoneware jars with tops can be used. Sturdy gloves, a scoop, squeegee, and a dustpan should be kept handy. Mercury requires special attention. Suction is the recommended method for picking up most small spills. The problem arises from vaporization of traces left in crevices. If spills are rare and occur where there is reasonable ventilation, the concentration of toxic vapors is not likely to exceed recommended exposure limits. Few stockrooms have ideal ventilation, however. As far as possible, always keep plastic trays under mercury containers or equipment containing mercury. Further information on cleaning up chemical spills will be found on pages 27-29 of "Safety in Academic Chemistry Laboratories." Safety Tips will address the question of selecting safe demonstrations and lab exercises in future articles. Readers are encouraged to share experiences, problems, and questions relative to all aspects of safety with their colleagues. American Chemical Society, 1155 Sixteenth St., N.W., Washington, DC 20036.
Volume 59
Number 2
February 1982
157
