in the Chemical laboratory Edited by NORMAN V. STEERE. School o f Public Health, University of Minnesota, Minneapolis, Minn., 55455
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XXXV. A Laboratory Safety Orientation Lecture for the First Chemistry Course JAMES R. IRVING, President, Stonsi Scientific Co., 123 7 N. Honore Street, Chicago, Illinois 60622 Turning beginning chemistry students loose in a laboratory without prior safety orientation may well he akin to giving a. new high-powered automobile to someone who does not know how to drive. Perhaps the greatest point that must be made to m y group of uninitiated students is that there are no such things as "beginning sulfuric acid" or "elementary hydrogen sulfide gas." The fact is that whether students are properly oriented and made aware of potential dangers or not, the seriousness of possible injury to the learner remains just ss significant. "When you heat something, it's hot" is truly a silly, naive statement to those who teach sdvanced chemistry courses, hut the fact remains that most injuries in beginning laboratory sessions are bums. They are, for the most part, occasioned through the student's lack of appreciation of that mundane statement-"when you heat something, it's hot." Teaching experience documents that the prevention of injuries and the maintenance of an accident-free history in the high school and junior college labor~tory is strongly dependent upon the teacher's preoccupation with a period of safety orientation priw to any work in the laboratory. I t soon becomes apparent that even the most innocent steps in manipulation of apparatus, instruments, and reagents are thoroughly important when the learner has had no experience with such methods. (Here, deliver us from the student who has "had a chemistry set a t home for many -Editor's
years and therefore knows just what to do!") To aid in developing the laboratory safety orientation period, a list of some 41 highly significant safety checks was evolved ranging from "wearing of protective glasses and apmns" to "collecting gases lighter than air." Just prior to the completion of an introductory chemistry course, several hundred students were presented with this list of techniques and habits related to chemistry laboratory safety. They were asked to choose the ones they believed would be the most significant. The list of techniques and habits ranged from the proper method of mixing acids with water, the handling of emergencies, the thomugh reading and understanding of the purpose of an experiment before beginning work, to the dangers of working with flamma,bl.bleliauids near an oDen flame. Interestingly enough, students did not feel that 'kttessing 'quiet' in the laboratory," "inserting finely divided solids into a test tube," or "using the mortar and pestle" were very important nor did they need special attention or instruction by the teacher. Origindly, the following techniques or safety laboratory habits were presented almost wholly by lecture demonstration with the aid of %fewcolored slides. Later, however, i t was found that preparing a set of some 80 slides to augument phases of the lecture demonstration wss foundhighly effective in teaching safety. Students may well be involved in making slides from year to year, thereby adding interest and impetus to the safety program.
Note
This contribution is provided as a guide to those teachers (high school and junior high school) who have the important obligation of introducing students to formal laboratory work. Readers will recognize much that is familiar; our publishing this in the "Safety" series adds our indorsement to the author's contention that safety is a reason for sound technique. What is described here is not a set of hypothetical admonitions. It is a presentation based upon student opinions and evalurttions of the actual experiments performed in a first course in chemistry.
Techniques The lecture demonstrator generally opened with a statement or two about the value of a small piece of toweling for holding and working with glass tubing, prior to the actual demonstration of how tubing is out and broken. A quickdemonstration of the cutting technique using the towel usually reinforced the idea of the cloth's effectiveness and need as a part of the student's laboratory equip ment. Just as valuable as the towel may he for cutting tubing and inserting tubing into stoppers, students were generally surprised to learn that glassware is not wiped dry but rather cleaned and drained dry as a. part of good lahoratory procedures.
James R. Irving strdird at Sorthwestern Universit,p, vhere he received h e Bachelor of Science degree and a. Master's degree in science education. Se taught chemistry a t the secondary md college level for twelve years and ;ewed for the last thirteen years with ,he Scientific Apparatus Makem Asso:istion, where he was Executive Secrea r y of the Scientific Laboratory 'urniture and Equipment Section. :n May 1966 Mr. Irving became Presilent of the Stansi Scientific Co., a nmufacturer of science teaching a p laratus and instruments. Mr. Irving is a member of the Na. i o d Association for Research in science Teaching and is active in work ~f the National Science Teachers Asso:iation and in the biologicel and physi:al sciences, inchtding the Central Lssociation of Science and M a t h e natics Teachers. For the past 25 years, Mr. Irving has ;ewed NSTA as a n evaluator of busi~esssponsored science teaching msi erials, pointed up the need for better icienceoriented vocational counseling ~ n has d worked far improved communiations between research and develop nent laboratories and top manage nent.
Such a. simple item as noting that a. test tuhe should never be more than one-third to onehalf full a3 a. protection against boil over and spatt,ering has paid for itself thousands of times in eliminating eye injuries and skin burns. After the test tube is filled with some colored water to help illustrate the step (Conlinued on page A H @ )
Volume 44, Number 3, Morch 1967
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above, is an ideal time to light s. bmnsen burner and show how such a tube properly filled should be heated. The instructor moves the tuhe through the &me slowly, and calls attention to the fact that such a technique prevents hot spots and consequent boil over. The teacher also is careful to point out that test tubes, when used in this manner, are not aimed a t onle's laboratorv uartner-r for that matter the student working on the other side of the bench. The teacher points out the simple fact that hot test tnhes should he placed in test tuhe racks rather than laid down an bench tops. Flasks, either Erlenmeyer or Florence, should be clarn~edto rine stands a t all times. The initnrctor uoints out the
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ing. Lahamtory forceps should he illnstrated as an extension of the student's fingers and a t the same time one of the learning student's most important safetjr tools for such exercises ss burning magnesium rihhon and the lifting and holding of small heated pieces of equipment. The combustion spoon is an integral part of many secondary school experiments, and its use shonld he illustrated by inserting red hot steel an01 into a hottle of freshly prepared oxygel~. (Strange as it may seem, thousands of camhustion spoons are still ordered each year from lnhoratory suppl? houses, and the illustration of their proper use seems justified an the heginniug chemistry level.) The use of the burner wing-top and hending glass-a fascinating phenomenon fop any beginning chemistp stndm~t-is ~.epentedillustrating good and had bends. In fact, here, the teacher may well go a step further and call attention to potential explosions that may occur if tuhing is poorly hent, thereby choking off gas or liquid emission through the tithe during the course of an experiment. Heating the tubing itnti1 the eu.-tomsry yellow sodium flame becomes evident and then ~tmovingthe tube from the flame to let it drop slowly by its own weight through the softening of the glass is ihown a ~ l dreshuxn as the proper techniqne for completing a 9f1° bend.
Equipment Identification Same teachers may question the value of identifying simple pieces of laharatory nppn~.atnsand equipment 8s heing related to lahorat,ory safety per se, but the fact remains that the uninitiated who do not know the difference between a. flask and a test tuhe are netusllg asking for trouble in the heginning chemistry Inh. A group of students used as a control were not given this phase of the orientntion safety lecture demonvtration and, interestiugly enough, the incidence of minor accidents and coosequent work prohlems during laboratory exercises increased tremendously in the first four-to six-week period. (Conlinaerl on page AP18)
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This d l prompts requiring the students to recognize and name the following simple pieces of equipment. To wpplement the laboratory manual and text, slides were made and used in covering this orientation. Bunsen hnrner Beaker Test tube, including rack Flasks (Erlenmeyer and Florence) Evaporating dish Rine stand ~ r a i u a t e dcylinder Crucibile and cover Crucibile tongs Laboratory forceps Test tube brush Nest of watch glasses Wide mouth bottle Funnel Asbestos hoard Combustion spoon Bulb pipet Colored coding used on carboys and other containers Thistle t h e True, the above list may look uncalled far-nd the more sophisticated an instructor becomes, the more naive this d l appears-but to the student who has never seen and handled these pieces before they are new.
Techniques Continued Much attention is given to the correct lighting and use of the Bunsen boner. Here, specific attention is given to beckfiring of the burner and the cdling of students' attention to an example of backfiring. (Even the wrreet technique of striking a match before the gas is turned on, and holding it alongside the top of the homer barrel is called to his attention.) Special attention is called to the movement of the burner in certain instances when a test tube containing reagents is mounted and/or fixed to 8. ring stand. The entire experience of cutting glass tubing is repeatedly illustrated, indicating once again, the value of the piece of toweling and how it is used. A new triangular file is used to scratch the tubing and-holding both ends short with the toweling-the student is shown haw these pieces are broken away from him. This of course is an excellent time to illustrate how the ends of freshly-cut glass tubmg are fire polished. Believe it or not, a. ~otentiallydangerous explosion was prevented because someone noticed the fact that instead of the tithe's end being fire polished the end of the tube was actually sealed. Some may question the safety connotations of placing hat tubing on pieees of asbestos rather than bench tops, and reference to the yellow sodium flame as an index of when tubing is ready for bending, but experience teaches that rather than questioning whether these so-called helpful hints are safety related, lack of their knowledge is involved or may (Continued a page ASeO)
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be the causative agent of a consequent laboratory accident. Water or glycerol should be used as a lahricant when inserting glass tubing in stappem. Here the value of toweling is recalled and illustrated and shown in the protection of fingers holding the tube short. This, of course, also applies t o the insel; tion of thistle tubes in ruhher or cork stoppers. Pouring from s, reagent bottle is prohnhly oue of the most common procedures performed in a. chemistry laboratory. The instmetor should note bhis by carefully illust,rating how the glass stopper is lifted between the index mrd middle finger and held with the entire hand grasping the bottle. The reagent is then poured and the stopper is replaced in the bottle, ineluding washing of hottle m d hands. (See Fig. 1 . )
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Fig 1 .
Collect technique for pouring from a
reogent
bottle.
The smelling or delectiw of odors is an integral part of many lnhoratory exercises, as safety orientation procedure carefully poinbs out and illust,rates wafting possible odor by hand to nostrils. Direct inhalation of vapors could easily damage the sensitive mucous memhrane af the nose and throat, not t o mention the fact that ill many instances inhalation of high concentration of vapors may he toxic and potentially dangerous. The role of the apat,uln is shown in extrsctiug solid reagents from hottles. A stec-hv-steo orocedore is illustrated to paper cup. While i t may he quoslioned whether demonstrating t,he pmper technique for filtration $safety related, poor techniqms and habits in this area are the cause oi lahorabory mishaps and accidents. Hence, filtrat,ion is included in the orientation s a f e t , ~demonstration beginning with the proper folding of filter paper-howing that a drop or two of water in the funnel will help the paper stick to the glass hefore filtration. Here, too, i t is nuled that, the heveled edge of the funnel should he touching the iuside wall of the heaker. Identifying the precipitate and the filtmle may not he considered %fet.y oriented" but accidents could occur if the studcnt does nut understand the difference be-
(Continued a page A Z 2 )
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tween the t w e t h e r e f o r e they are identified and taught. as such. The significance of the Bunsen burner's blue cone flame tip plheed immediately beneath the wire gauze and evaporating dish is shown as the proper way to evaporate a filtrate to dryness. Once again, the use of crucibile tongs is reinforced in the student's mind when the teacher illustrates their use in the removal of the evaporating dish from the wire gauze after heating. The role of the piece uf toweling is shown in removing beakers containing hot water or reagents from the ring stand, i.e., using a. piece of folded towel wrapped around the top of the beaker and held tightly by thefingers. (SeeFig2.) Beaker tongs may also be used for this operation. -'
Fig 2. A piece of toweling, doubled, w r a p p e d around a hot beoker m a y b e pinched tightly to form a rofe method of handling thir particular piece of glorrware.
The point that hot apparatus or equip ment should not he returned to student drawers or tote trays is emphasised by rinsing hot beakers with cold water to reduce their temperature. The rule is applied that if the glassware is too hot to hold in one's hand, it is probably too hot to be returned to the drawer. The removal of spilled mercury should be an especially cogent part of any lahoratory safety lecture. Retrieving the mercury should be demonstrated by the instructor using one of several recognized methods. This phase of the demonstration gives the teacher a good opportunity to point up the importance of mercury clean-up and the fact that mercury is toxic and is especially dangerous because of its volatility.
Habits Several habits related to laying the foundation for a. safe labomtory become obvious through working with the uninitiated student. These include the following: 1. Wearing safety glasses, aprons, and
(Continued npage A B 4 )
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protective sleeves should become habitual to students working in the chemistry laboratory. 2. Careful reading of reagent bott,le labels. There is a great difference indeed between potasium chloride and potassium chlorate, between mercurous chloride and mercuric chloride, between manganese and magnesium. 3. Long sleeves should he rolled above the wrists as a definite safety habit. 4. Talking is permitted if control and restraint is practiced. 5. Studying the PURPOSE of an experiment becomes one of the most important steps of beginning chemistry laboratory practice. 6. I t should be emphasized that test tubes or any pieces of equipment which have s. potential for expelling a, gas or liquid should be pointed away from the bench partner or fellow worker. 7. Students should instinctively check all glassware for cracks prior to use. 8. Glassware of all types should be placed a t the back of the laboratory bench to prevent falling and unnecessary hreakage. 9. When it becomes necessary to carry long pieces of glass tubing, the student should be instructed to hold it vertically when walking through the laboratory. 10. ALL INJURIES, REGARDLESS OF HOW MINOR, s H o u L n BE REPORTED TO T H E INSTRUCTOR IM.
11. I n all csses of diluting acids T H E ACID SHOULD ALWAYS BE ADDED TO T H E WATER. The teaching of this ~ h a s eof safety as a. habit rather than a ''diluting tec6niaue" becomes amarent .. t o the experienced teacher. 12. The laboratory hood should he used wherever there is a question of toxicity of a by-product gas or when poisonous or toxic gases are used as a part of sn experiment. (Yes, H2S is more toxic than HCN.) 13. Drains should be thoronghly fluihed after spilling out reagents. 14. Good Housekeeping is imperative in the chemistry laboratory, and the use of a floor crock for broken glassware and other disposable items should be emphasiaed-in the case of alkali metal s a a p a kerosene-filled bottle shauld he aveilable for storage or disposal of the material.
Special Safety Duty Implications for the Chemistry Teacher The chemistry teacher has no higher duties than any other teacher, but the greater hazard potential encountered in the chemistry laboratory, as compared for example with the language laboratory, obviously requires more diligence in preventing accidents. Similarly, more care is required in industrial fihops and laboratories than in offices and more care is required in driving than walking. The chemistry teacher will fulfill his accident prevention responsibilities if he
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conducts the same type of safety program expected of every supervisor in industry: 1. Have a thorough undentanding of the potential hazards of all the materials, processes, and equipment that will be in the school laboratory. 2. Fully instruct every pupil in the necessary laboratory safety requirements, established as a condit,ion of participation. Check students' understanding of these requirements with carefully-developed writ,ten tests, signed by the pupil and kept on file; a near-perfect scorn should be required for participation in laboratory activities. 3. Supervise the daily activities of pupils in laboratories closely enough to be reasonably sure of good compliance with safety requirements. Take (and keep a record of) disciplinary action for any willfull violation of safety rules. lieinstruct as necessary to ensure complete understanding. 4. Take prompt action to correct ally unsafe conditions and practices. Inform the school administration in writing of any unsafe condition the teacher cannot himself correct; suspend related student activities until the condition has been carrected. No task should be deemed so important that it may be knowingly done unsafely.' Two supplementary related references should be of furt,her interest to the chemistry instructor. They include an excellent article by Myron Stettler. Attention is called to techniques and errors commonly noticed among beginning (high school) chemistry students. The author points up four categories: heating, weighing, filtering, sndmiscellaneous. ("Safety First. . O r First Aid," December 1859, The Seienee Teaehw.) While many instructors may wish to produce their own set of visual aids, 35 mm slides and other demonstration materials, Chemisl~ymagazine lists 16 mm sound films illustrating laboratory techniques and practices. Subjects range from "Introduction to the Chemistry Lahoratory" to the "Test Tube" and "Handling Chemicds." This outstanding list is .wailable from Association Instructionnl Materials, c/o Association Films, Inc., 347 Madison Avenue (Dept. DC), Piew York, N. Y. 10017. (Chemirky, 38, No. 1, pp. 28, January 1965.)
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lSafely Newsletter, National Safety Council, Chemical Section, "LiahiMy of Chemistry Teachers," May 1006.
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