CHE 450G SAFETY EXAMINATIONProcedure: Before laboratory work in CHE 450G begins a student must pass the SafetyExamination. A copy of the exam with answers is given to the new student by thegroup safety officer to study. When the student is ready to take the examination, thecopy with the answers is returned and the student is supplied with a copy of the examwithout answers. The test is administered by the TA in a location of his or her choice.The test is to be taken in private without outside resources. No time limit is imposed. The exam is to be graded by your TAs prior to beginning scheduled laboratoryexperiments. If incorrect or incomplete answers are given, the TA and/or instructor willreview these areas with the student. The graded and reviewed exam is then passed onto the instructor. The TAs will then return a copy of the exam with answers to thestudent for future reference.1Safety Exam QuestionsPart I. General Lab Safety1. What safety references should you consult to assess the hazards of achemical or planned experiment?The chemistry library has several texts on safety in the reference section:Prudent Practices in the Laboratory on-line summaryhttp://www.hhm:.org/science/labsafe/lcss/start.htmSafety in Working with ChemicalsSigma-Aldrich Library of Chemical Safety DataMerck IndexAldrich CatalogOn-line MSDS sheets:Univ. of Ill. MSDS telnet://romulus.ehs.uiuc.edu:3000Fischer Scientific MSDS http://www.fischer.com:/cat.htmlSafety TechLine 1 800 356-25012. What steps should be taken when injured in lab?Get TA and instructorStop bleeding if necessaryWash affected area with cold water (if chemicals are unreactive withwater)Seek medical attention as necessary3. Compressed gas cylinders are quite common in inorganic labs. Discusstheir handling, use, and transport.Even if a gas cylinder contains an inert gas, it should be handled carefullybecause of the high pressures involved. Tanks should always be strapped orchained to a stable surface and should only be moved on a cart designed totransport them. A metal valve cover cap should enclose the valve before moving as well. Each type of gas requires a particular regulator. Oxygen tanks inparticular require regulators free from hydrocarbon grease. Teflon tape shouldnever be used.4. General vocabulary as seen on the Safety Examination (answered verballyto the group safety officer):Dewar AspiratorsVacuum pump Schlenk line2Alkali metal Rotary evaporatorMercaptan Heating mantles (Variacs)Base bath/Acid bath PhosphineBleach5. How should you dispose of the following reactive wastes? (each shouldbe done in a well-functioning ventilation hood while stirring the mixtures)For more detailed descriptions see Prudent Practices for Disposal ofChemicals from Laboratories and/or http://www.chem.uky.edu/resources/stockroom/waste.html/a. Oxidizing agents (chromates, permanganates, chlorates, etc.)Acidify a dilute solution (<5%) to a pH<3 with sulfuric acid and slowly adda 50% excess of aqueous sodium bisulfite.b. Sodium borohydrideAdd water slowly until the solution is less than 3%. Add excess aqueousacetic acid dropwise with stirring under nitrogen.c. Mercaptans and sulfidesAdd a 25% excess of bleach to oxidize these compounds with stirring;sometimes a more concentrated bleach substitute, calcium hypochlorite(swimming pool chlorine, HTH brand name) can be used. For a moredetailed procedure see Prudent Practices for Disposal of Chemicals fromLaboratories page 65.d. Alkali metals (a major source of laboratory fires)Add 3:1 kerosene:isopropanol or tert-butanol slowly while stirring. Aftergas evolution ceases, often several hours or days later, add 95% ethanolslowly with stirring. After the metal has been consumed, and no largesolids are evident, add cold water slowly while stirring. Slowly add a 5%aqueous HCl solution until aqueous layer is neutralized (pH ~ 7). Placeorganic layer into the non-halogenated waste jerry can and pour theaqueous mixture down the sink so long as no solids are visible.e. Metal sulfidesAdd slowly to ice water. Keep in hood-H2S evolution.f. Nonmetal halidesHydrolyze these compounds by slowly adding them to a stirred 2.5 Msolution of sodium hydroxide.3g. Metal carbonylsOxidize these compounds with bleach.h. Nonmetal alkyls (BR3, PR3, AsR3, etc.)To a dilute (<5%) solution (of the alkylating agent in an inert solvent),slowly add a 10% excess of tert -butyl alcohol in a high-boilinghydrocarbon solvent such as heptane under nitrogen. Add cold water andthen 5% hydrochloric acid.i. Organomercury compoundsOxidize these compounds with bleach.Part III. Fires and explosions: Prevention and extinguishing.1. There are four general classes of fires which are likely to pose a genuinethreat to your laboratory safety. What are the four classes of fires and whattype of extinguisher is required to put out each fire? Additional information isgiven below for your benefit, but you need only answer the highlighted questionabove.Class A fires: Ordinary combustible solids: paper, rubber, textiles. Frequently accompanied by destructive distillation producing flamingvapors or toxic gases. Also may leave hot ash or residue which mayinitiate ignition. Effectively extinguished by water, which isrecommended if the water poses no further hazard. Also extinguished byCO2, N2, volatile halocarbons (CF3Br, etc.), and dry chemicalextinguishers, though these may spread ashes due to rapid release ofcompressed gas from the extinguisher cylinder. Dry ice will usually rapidlysmother these fires if it is readily at hand.Class B Fires: Involves flammable liquids.Spreading of the fire is a major complication which is commonlyencountered if a vessel of flaming liquid is overturned or broken. Easilyextinguished by the exclusion of air by covering it in an upright vesselor by blanketing in foam, CO2, N2, volatile halocarbons, or4sometimes dry chemical (depending on the situation). Again, dry ice orliquid nitrogen is very effective if it is at hand. Compressed gasextinguishers can lead to spreading and worsening of the fire if the forcefrom the extinguisher overturns a vessel containing the flammable liquid.Class C Fires: These are Type A or B fires in which