























Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
51 short questions on lab chemistry with answers
Typology: Lab Reports
1 / 31
This page cannot be seen from the preview
Don't miss anything!
1. One of the major hazards which face a laboratory chemist is that of fires. It is necessary that each worker know the location of fire extinguishers and fire alarm pull stations. It is also very important to know the types of fire for which various commercial extinguishers are designed. There are four general classes of fires which are likely to pose a genuine threat to your laboratory safety. List each of the classes of fires and the type of extinguisher which would be required to put out the fire. ANSWER : Class A Fires : Ordinary combustible solids: paper, rubber, textiles. Frequently accompanied by destructive distillation producing flaming vapors or toxic gases. Also may leave hot ash or residue capable of re-ignition. Effectively extinguished by water which is recommended if the water would pose no further hazard. Also extinguished by CO 2 , N 2 , volatile halocarbons (CF 3 Br, etc.) and dry chemical extinguishers though these may lead to spreading ashes due to rapid release of compressed gas from the extinguisher cylinder. Dry ice will usually rapidly smother these fires if it is rapidly at hand. Class B Fires : Involves flammable liquids. Spreading of the fires is a major complication which is commonly encountered if the vessel of flaming liquid is overturned or broken. Easily extinguished by the exclusion of air by covering if in an upright vessel or by blanketing in foam, CO 2 , N 2 , volatile halocarbons or sometimes dry chemical (depending on the situation). Again, dry ice or liq. N 2 is very effective if it is at hand. Compressed gas extinguishers can lead to spreading and worsening of the fire if the force from the extinguisher overturns a
vessel containing a flammable liquid. Class C Fires : These are Type A or B fires in which electrical equipment is involved. Can be treated as class A or B if the power is turned off. It is a better practice never to use water as an extinguisher, even in the event power is disabled (some electrical equipment will store charge). If the power cannot be turned off the fire must be extinguished with inert gas or dry chemicals. Again, dry ice or liq. N 2 is very effective if available. Class D Fires : These fires involve reactive metals (e.g., Li, Na, K, Zn, Al, Mg, etc.) or active hydrides (NaH, KN, LiAlH 4 , etc.). These fires cannot be extinguished by CO 2 or H 2 O) or volatile hydrocarbons. Inert powder must be used (sand, talc, or alkali metal salts). Bicarbonate base extinguishers may not be effective. Metal-X extinguishers are recommended. 2. Chemical hazards are also a problem in the laboratory and it is important to know the hazards you might encounter in a lab. If you are working with a chemical and you do not know the hazards associated with it, you should ask your supervisor or consult the references listed at the beginning of the quiz. Name some common hazards associated with chemicals. ANSWER :
4. What does the fire alarm sound like and what is its function? ANSWER : These alarms are loud clanging bells throughout the building. They call the University Police Department and alert occupants to leave the building. 5. In the event of a fire, chemical spill or other emergency, appropriate safety equipment should be easily accessible and an emergency response plan initiated. What are appropriate circumstances for using fire fighting equipment and indicate an initial response plan that you should follow? ANSWER : Lab personnel should attempt to put out only small fires when they are confident the fires can be extinguished rapidly and when they themselves are not endangered. They should then notify the University Police Department and Chemistry Department Safety Committee to report the fire and use of equipment. In the case of large fires, you should immediately call the Police at 911 or use one of the hallway emergency response telephones, activate a fire alarm to evacuate the building and meet the firefighters at the building entrance (by the receiving dock) to direct them to the fire. A similar initial response plan should be instituted for large chemical spills. 6. In the event of an accident, health-related or other emergency, appropriate first aid and an emergency response plan should be initiated. What are appropriate circumstances for using first-aid equipment and an initial response plan that you should follow?
First aid should be administered, if possible, to a person who is injured or ill to prevent death or further injury until professional medical help arrives, only if this poses no threat to yourself. This includes removal of the victim from the source of the injury and control of life- threatening conditions such as bleeding or shock and lack of breathing or heartbeat. In the case of an accident or emergency health problems you should immediately call University Police at 911 or use one of the hallway emergency response telephones, and meet the emergency personnel at the building entrance (or by the receiving dock) to direct them to the emergency. 7. The fume hoods in the labs are designed to operate in conjunction with the ventilation system for the building. The hood doors should always be kept at the appropriate level when you are not actively working in the hood area. (Under no circumstances should the hood doors be removed.) This will aid in the proper ventilation of the building and help prevent contaminated air from re-entering the lab. The hoods should always be on, but in the case of certain types of fires the hood may actually serve to fan the fire making it difficult to extinguish. One cutoff for each hood is located in the penthouse service area but there is no cutoff in your lab area. In the event of a fire emergency, how should you leave your hood area and how should the hood sash be positioned? ANSWER : If possible you should pull the hood sash to the closed position before leaving you lab area.
potentials as high as 208 volts. Frayed electrical wires could easily cause a very dangerous exposure to high voltage. 10. The storage of solvents in a chemical laboratory may pose a serious hazard to the safety of the laboratory personnel. Waste solvent collected in the lab should be properly labeled, tightly capped and should regularly be removed from the laboratory area for disposal. Solvents used and reused in large quantities must be adequately stored in nonbreakable containers (fireproof if the solvents are flammable) and under no circumstances should multiple (more than one) glass gallon containers be used for solvent storage in a single aisle. There is also a 10-gallon upper limit for flammable solvent storage in a lab. The department of Environmental Health and Safety has a regular solvent disposal system. Solvents for disposal are best stored if the containers used are fireproof cans or polyethylene jerricans, and are closed and properly tagged or labeled. Outline the reasons for use of these types of containers and the solvents which should be kept in each. ANSWER :
examples. The polyethylene containers will provide protection from corrosion from the solvents with no danger of breakage. 11. Broken glassware poses a serious threat to your laboratory safety. Frequently, people are cut by broken drip tips on funnels or by glass tubing which has not been fire polished. What precautions should you take in this regard? ANSWER : Broken glassware must be repaired immediately so that there are no exposed sharp edges. When cleaning up broken glassware be sure to use protective leather gloves. In some cases broken glassware should never be handled directly (e.g., a broken flask which contained ethanolic KCN). Such equipment should be cautiously swept into a dustpan or similar equipment. A clean and neat bench reduces the likelihood of breakage. Unusable broken glassware or pipettes should be collected in a labeled glass waste disposal box. When full, notify your maintenance cleaning person for disposal. 12. Due to the building's ventilation system, the internal pressure of the building is less than the outside pressure. Since the drainage system is vented to the atmosphere on the roof, it is easy for odors and noxious gases to be swept back into your lab through open sinks and floor drains. How can this be avoided? ANSWER : Keep all sink traps filled with water and regularly check infrequently used floor drains and cup sinks. Do not pour noxious substances with high vapor pressure down the drains (solutions of H 2 S, mercaptans or
use with lasers and other radiation emitting equipment. A complete face shield should be used in particularly hazardous procedures (e.g., the generation of diazomethane). 15. To keep the air circulation in your hood working properly and to reduce the chance of initiating dangerous electrical fires in your hood, the hoods have been designed to allow routing of cords and cables in a special way. What features are available? ANSWER : Wires, cords or tubes should not be routed between the doors or out either side of the hood face. There is a flap at the front of each hood which is designed for the passage of wire or cords which will not alter the air flow. The shelf under your hood is the proper place for Variacs and other non-explosion proof electrical control equipment. 16. In the event of a laboratory accident, what sources of help will always be available? ANSWER : The University Police Department is available to assist in emergencies 24 hours/day by dialing 911 from any University phone. The University Police dispatcher will contact the most appropriate emergency response personnel and send them to your aid. When using this number, it is always important to let the emergency dispatcher hang up first. This will verify that the dispatcher has all the necessary information. 17. Unlabeled chemicals are a very dangerous hazard in the lab. Labels should always be securely placed on stored chemicals. Even if
you think you can remember, don’t trust your memory -- something could happen to you to prevent you from identifying these materials. Also, we have no mechanism for disposing of unknown chemicals (current regulation of the U.S. Environmental Protection Agency makes it illegal to dispose of any unknown chemicals), so someone will have to identify the chemical before it is disposed of. Identification may be difficult, dangerous, and expensive. If you find unlabeled chemicals in your laboratory, how should you treat them? ANSWER : They should be disposed of properly and promptly and not stored indefinitely as frequently happens in refrigerators. Identify the chemical to the best of your ability (consult your co-workers and research adviser as a first step). Particular hazards should be noted on the label (explosive, pyrophoric, highly toxic, etc.). The material should then be taken to the hazardous waste collection site. 18. The clothing you wear in the laboratory is a factor which will influence your safety. Outline the do’s and don’ts of the clothing worn in a chemical laboratory. ANSWER :
20. A properly designed and supported lab shield should be used when working with pressurized equipment or reactions which are known or suspected to be potential explosion hazards. These shields are a necessary supplement to the explosion protection offered by your hood design. Explain the explosion protection afforded by your hood. ANSWER : The doors to the hood are made of laminate safety glass to be blast resistant. There is also a blast vent on the top front of the hood which will be blown open during an explosion, thus providing an outlet for the blast force while directing it up and away. 21. In the event of chemical splashes or spills it is urgently necessary to thoroughly flush chemicals from contact with your skin. For spills on your hands or arms you will usually be able to wash the chemicals off over your sink. Remember you should use cool water to rinse with since warm water will open your pores making systemic absorption faster. The affected areas should be washed for at least 15 minutes. For large chemical spills or contamination in or around the eyes, each lab should have access to a safety shower and an eye wash. Where are these located and how are they marked and used? ANSWER : Contact of Chemicals with the Eyes: Take the victim immediately to the nearest eyewash station. Flush the eyes for at least 15 minutes. Eyelids must be held open with the eyeballs continuously rotating for optimum flushing. Immediately call Public Safety at Ext. 911 for additional assistance.
Contact of Chemicals with the Skin over a large part of the body: Help the injured person to the safety shower, and flush skin exposed to the chemical for at least 15 minutes. Remove all layers of contaminated clothing, shoes, and jewelry. If clothing or jewelry adheres to a chemically-burned area of skin; do not pull it away. Immediately call University Police at 911 for additional assistance. Contaminated clothing should be removed. It would be desirable for there to be a change of clothes in the labs for such emergencies. Sweats are recommended because of the size adjustment. 22. Compressed gas cylinders can pinwheel or rocket through masonry walls if the regulators or valves are broken off and can explode if substantially weakened structurally. What precautions can be taken to avoid rocketing, damaged cylinders? ANSWER : Cylinders should be firmly secured at all times with a belt or chain and capped when not in use. An appropriate hand cart with a cylinder strap should be used for moving cylinders. Cylinders should be kept away from sources of heat or ignition. Routinely check for leaks. 23. Chemicals should be separated from each other by hazard class, whenever possible to avoid unwanted reactions in the event of a fire or due to leaking or broken containers. Acids should always be separate from cyanides and from bases, while oxidizers should always be kept away from organics and reducers. Carcinogens should be stored in ventilated cabinets. List the five hazard classes recommended for segregating chemicals in storage.
which would likely endanger building occupants. What procedures can be followed to minimize the chance of breaking glass bottles? ANSWER :
Environmental, Health and Safety Office recommends emptying the containers regularly regardless of how full they are and using polyethylene jerricans for collecting both halogenated and non- halogenated waste solvents. Why shouldn’t metal safety cans or glass bottles be used for collecting waste solvents? ANSWER :
1.Personal safety -- if someone comes into contact with a non- water reactive chemical, immediately rinse the affected area thoroughly with water for at least 15 minutes and contact Public Safety at Ext. 911. Wear appropriate personal protective equipment when cleaning up the spill. 2.Containment of the spill -- close lab doors and windows. Outline the area of the spill with spill adsorbent. Use Activated charcoal (organic solvents spill), sodium bicarbonate /speediDri (acid spill) or Citric acid/speediDri (base spill). Containers of these materials are available in each emergency closet located in your research areas. Adsorb the spill -- begin to adsorb the rest of the spill with the appropriate adsorbent. Use a dustpan or scoop to stir the mixture. 3.Cleanup -- for solvents, scoop the spill mixture into a plastic bag, label the container, and call Environmental Safety and Health at 777-2211 for pickup. 4.Neutralize the spill