JEFFREY M. STA. INES, Ph.D. Science & Chemistry Education

JEFFREY M. STA. INES, Ph.D.Science & Chemistry Education

First hand laboratory experiences make science come alive.

In order to make this experience safe and successful, it is necessary to be alert and aware of some problem sources.

Common lab accidents include cuts, spills, burns and falls; basic safety precautions will do much to prevent such accidents.

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Preservation and Storage of Materials

GlasswareThe size of the items of glass apparatus stored

should be standardized as far as possible. They should not be placed too high and mixed with heavy apparatus or metal articles. Tall glass apparatus should be stored at the back of shelves and smaller pieces in front.

Glassware is stored according to its type and size. All flasks, for instance, should be stored in neighboring bins but separated according to size.

Preservation and Storage of MaterialsFlat-bottom vessels may stand upright but round-

bottom vessels should be stored in a bin with high front.

Small glassware, such as clock glasses, specimen tubes, Petri dishes and microscopic slides, are best kept in shelf trays.

Burettes require a long padded drawer or a stand. All expensive glassware should be separately packed in soft wadding.

Thermometers should be kept in their cardboard-cases and store according to type and range.

Preservation and Storage of MaterialsGlass Tubing and RodsHorizontal storage for glass tubing or glass rod is

undoubtedly the best. The tubing must be well supported along its length

to prevent sagging which is often noticeable in glass tubing which has been stored vertically.

Large-diameter tubings must be plugged at the ends to keep out dust.

Soda dust and hard glass should be kept as far apart as possible.

Preservation and Storage of MaterialsGlass tubing should be stored by “weight” (i.e., light,

medium and heavy wall) and each weight of tubing is stored according to its outer diameter.

It is convenient if a table of sizes, including wall thickness and allowed tolerances is hung close to the glass tubing storage racks.

The tubing is normally delivered in 1.5 m lengths and keeps much cleaner if stored in its original packing.

Preservation and Storage of MaterialsPlasticsPlastics apparatus should be stored away from heat

sources. If it is brittle, it should not be stored with heavy apparatus.

Metal Wares Metals wares such as clamps, bossheads, tripod

stands, Bunsen burners should be stored together and they need periodic maintenance.

Preservation and Storage of MaterialsApparatusThe numerous small items found in the laboratory

are usually kept in drawers or trays.Optical items such as lenses, mirrors and prisms are

kept in drawers with packets of silica gel to maintain dryness.

Bigger apparatus are always arranged in shelves. Those heavy ones are placed below and the lighter ones atop of the shelves.

Teaching aids are usually stored in cupboard with visible windows.

Preservation and Storage of MaterialsElectrical PartsElectrical equipment and components should be

stored in a group, away from fumes and chemicals. Valves, transistors, and other delicate items should be wrapped in cotton wool and placed in individual casings.

The school laboratories house expensive science equipment and chemicals which could get damaged rapidly through dampness of ceilings and walls of storerooms.

Regular inspection on the laboratories and equipment prevent this.

The frequency is at the discretion of the senior science teacher. Such efforts bring about efficient services to science teaching in schools.

Inspection and Maintenance of Laboratories and Equipment

Inspection Book For each laboratory inspection a record must be made in

the laboratory inspection book of repairs to be done on items like windows, gas taps and furniture.

Action must be taken immediately as delayed action could result in further deterioration in the condition of the item, and then a major repair will be necessary.

PaintworkCarry out touch-ups of paintwork of the laboratories and

facilities to check deterioration until the usual general painting carried out.

Inspection and Maintenance of Laboratories and EquipmentLightingMost school laboratories have glass louvers. When glass panes are

used, sunlight gets in, heating up the science laboratories, and the reflection of light from bench tops can give distracting glares. The use of curtains or bamboo blinds overcomes this problem.

Laboratory doors are required to be kept open at most times. Too often the doors are closed because the door hooks, which have been damaged, have not been replaced. Closed doors shut out light and cut ventilation and can cause safety hazards.

Faulty ceiling lamps must be attended to immediately. In most cases the faults are due to ‘fused’ bulbs, fluorescent tubes or spoilt starters. A stock of these items must be kept to meet emergency.

Inspection and Maintenance of Laboratories and EquipmentVentilationScience laboratories require good ventilation,

especially the chemistry laboratories. It is good practice to keep louvers and doors open. Ceiling fans, suctions fans and fume-cupboard fans help tremendously in the ventilation of laboratories. Therefore they must be kept in good operational condition.

Ceiling fans require minimum operation care. They must be kept clean and when the regulators are worn out, get the contractor to change them.

Inspection and Maintenance of Laboratories and EquipmentSuctions fans should be cleaned regularly

and lubricating oil applied sparingly.Fume-cupboard fan units are normally

sealed to protect them from corrosive fumes. It is important to keep them in good working order. When a fan fails to work get it repaired immediately.

Inspection and Maintenance of Laboratories and EquipmentSinks Students have a tendency to throw solid and liquid

waste into the sinks despite repeated reminders to stop the bad practice. One good way to overcome this is to mount a strip of wood with three plastic containers.

It is found that students find it more convenient to use this system of disposal than the usual rubbish bins, hence less littering of the sinks. At the end of the working day the laboratory staff go round to clear the containers.

Inspection and Maintenance of Laboratories and EquipmentPorcelain sinks are easily stained by chemicals.

Stain marks are readily removed by rubbing with cleansing powder. A persistent stain however can only be removed by treatment with a mixture of equal volume of concentrated nitric and hydrochloric acids. Naturally care should be taken especially with fumes.

Sink traps need periodic cleaning out, this reduces untimely choking up of sinks during laboratory lessons.

LABORATORY SAFETY RULES

Accidents in a science laboratory can be minimized, if not completely avoided, when students consciously observe safety rules.

1. Eye Protection:

All students must wear safety goggles or industrial quality safety spectacles in laboratories, where chemical work is done.

2. Warning Signs:

“No smoking,” “Caution – Radiation Area” or other warning signs must be strictly obeyed.


3.Horseplay:Horseplay and practical joking of any kind is strictly forbidden.

4. Labeling Containers:All containers of chemicals must be clearly labeled showing the name of the chemical, date, owner’s name, and safety precaution if hazardous.

5.Securing Compressed Gas Cylinders:Compressed gas cylinders must be secured with a strap or chain at all times.


6.Working Alone:No one should perform experimental work in a chemical laboratory unless a second person is present or located within calling distance.

7. Work Authorization:Unauthorized experiments are forbidden. Before any experiment is performed in an instructional laboratory, approval must be given by the instructor-in-charge. Experimental work in research laboratories must be a part of the program approved by the research director.


8. Radiation Hazards: Experimental work with radioactive materials or equipment generating ionizing radiation is strictly forbidden.

9. Reporting Accidents and Fires: All accidents resulting in injury, property damage, or fire must be reported promptly to the appropriate authority.

SAFETY HABITSSeveral habits related to laying the foundation for a safe

laboratory become obvious through working with the uninitiated student. These include the following:

1.Wearing safety glasses, aprons, and protective sleeves should become habitual to students working in the chemical laboratory.

2.Careful reading of reagent bottle labels. There is a difference indeed between potassium chloride and potassium chlorate; between mercurous chloride and mercuric chloride; between manganese and magnesium.

3.Long sleeves should be rolled above the wrists as a definite safety habit.

SAFETY HABITS4. Talking is permitted if control and restraint are practiced.

5. Studying the PURPOSE of an experiment becomes one of the most important steps of beginning chemistry laboratory practice.

6. It should be emphasized that test tubes or any pieces of equipment which have a potential for expelling a gas or liquid should be pointed away from the group partner or fellow worker.

7. Students should instinctively check all glassware for cracks prior to use.

SAFETY HABITS8. Glassware of all types should be placed at the back of the laboratory

bench to prevent falling and unnecessary breakage

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, SHOULD BE REPORTED TO THE INSTRUCTOR IMMEDIATELY.

11. In all cases of diluting acids THE ACIDS SHOULD ALWAYS BE ADDED TO THE WATER. The teaching of this phase of safety as a habit rather than a “diluting technique” becomes apparent to the experienced teacher.

SAFETY HABITS

12. The laboratory hood should be used whenever there is a question of toxicity of a by-product gas or when poisonous or, toxic gases are used as a part of an experiment, e.g., H2S, HCN.

13. Drains should be thoroughly flushed after spilling our reagents.

14. Good housekeeping is imperative in the chemistry laboratory, and the use of a floor crock or plastic pail for broken glassware and other disposable items should be emphasized – in the case of alkali metal scrap a kerosene-filled bottle should be available for storage or disposal of the material.

Common Chemical Hazard Symbols

DefinitionsBiological Waste - Biological materials of animal,

human, plant or microbial origin.Biohazardous waste – This can include infectious

material, contaminated agar plates, live cultures,human cells and blood, and disposables that have been in contact with the above.

Broken Glass bin – These are the yellow bins located within certain labs. The contents of these bins areplaced into the domestic waste stream, so should not contain any hazardous material.

Contaminated Materials Lab Bin – Bins located in labs for glass, filter paper, tissues, gloves which are notfree of hazardous material.

DefinitionsCytotoxic Waste – Any substance contaminated with

any residue or preparations that contain materialsthat are toxic to cells principally on their action on cell reproduction. Staff preparing cytotoxic drugs forexperimental purposes are at risk of dermatitis, allergic reactions, cytogenic abnormalities, carcinomas,mutagenic effects to cells, etc.

Domestic glass - Glass not in use in the laboratory such as coffee jars, glass drink bottles.

Laboratory glass – Glassware specifically designed or used for laboratory work.

Hazardous waste container, liquid – 5L HDPE available from dry store

DefinitionsSharps – Objects or devices that have acute,

rigid corners, edges, points or protuberances capable of cutting or penetrating the skin e.g. hypodermic needles, glass, scalpel blades and lancets. All sharps are hazardous because of the potential to cause cuts and punctures. Sharps may also be contaminated withtoxic, infectious or radioactive materials, which substantially increase the risk potential.

Winchester – Brown glass container, most often 2.5 L in volume, used to store solvents, ammoniasolution and concentrated acids.

Common Errors In Waste HandlingImproper Labeling of Waste ALL bottles of chemical waste must have

Hazard Form stickers with the start date and contents filled out.

Failing to label a waste bottle. If the contents of the bottle are not listed, the next person to use the bottle could accidentally combine incompatible chemicals causing a fire and explosion.

Common Errors In Waste HandlingStoring waste in a bottle lacking the words

"Hazardous Waste".Only these exact words must be used. "Organic Waste", "Xylene Waste" etc. are unacceptable. If something isn't really waste, don't put the word "waste" on the bottle. Label it "used" etc. Scratching out the former contents of the label on the bottle and writing "Waste" on it, is also unacceptable. You must remove or totally deface the old label so there is no confusion over the contents. To repeat, "Waste" is an unacceptable term. The words "Hazardous Waste" must be stamped or written on the bottle.

Common Errors In Waste HandlingImproper Storage of Waste Storage of waste in a fume hood where

reactions are being carried out.If your reaction gets out of control, the waste bottle could explode and lead to a catastrophic fire or mixing of incompatible chemicals. Always remove waste bottles from hoods where reactions are being performed.

Using metal cans for waste.Even near neutral pH, solids and liquids can easily corrode through metal cans in a surprisingly short period of time. Use only glass or polyethylene containers for waste.

Common Errors In Waste HandlingStoring flammable waste containers on a

bench or floor. Store your waste containers in a cabinet, preferably an explosion-resistant solvent cabinet.

Storing waste bottles in or near a sink or floor drain.This could allow toxic chemicals to enter the sewer, and emit toxic gas or explode.

Common Errors In Waste HandlingFailure to Cap Waste Bottles Leaving the cap off an organic waste

bottle.The only time a cap should be off a waste bottle is when you are actually putting waste into it. If you are afraid of a pressure buildup in the bottle, simply cap it loosely.Leaving a funnel in the waste bottle.This is unacceptable. A funnel can too easily be moved to an adjacent (incompatible) waste bottle and result in a fire or explosion. When you are done with it, cap it!

Common Errors In Waste HandlingAccumulation of Excessive Waste

Ideally, you should have no more than ONE bottle of each kind of waste in your laboratory. If the organic waste bottle is full, take it to the waste boot or waste storage area. There is no purpose in having several bottles of organic waste in your lab. If a fire were to occur, it would be much more serious.

Improper Segregation of Waste

Storing acids and bases in the same cabinet.Leaking containers or a spill could cause a violent reaction which would release large quantities of toxic gases. Storing acids and organic waste in the same cabinet.In the event of accidental mixing, a catastrophic fire or explosion could result.Mixing incompatibles in a waste container.For example, nitric acid and ethanol can form an explosive mixture.

How To Segregate Waste In The Laboratory

Proper segregation of laboratory waste is essential to good chemical hygiene and a safe workplace environment. Many workers often tend to put all of their wastes into the same cabinet or fume hood. Doing so can have disastrous results! The guidelines for temporary storage of chemical wastes in the laboratory are really no different than those that you use for the storage of your usual lab chemicals.


The most important rule is to make sure that any chemicals or wastes stored together are compatible with each other!

Therefore, proper segregation of wastes involves making sure that wastes within a bottle are compatible. Only chemically compatible waste can be mixed together and placed in a common container for disposal


Examples of compatibilityCan put in the same waste container bottle for disposal Flammable solvents acetone, methanol, ethanol, toluene, xylene, acetonitrile, benzene etc..(can all be put in the same disposal container) Halogenated solvents halothane, methylene chloride, chloroform, carbon tetrachloride, trichloroethane, trichloroethylene (can all be put in the same disposal container) Organic acids formic acid, acetic acid, propionic acid (can all be put in the same disposal container)


Examples of IncompatibilityCannot put in the same container bottle for disposal Heavy metal solutions aqueous solutions containing arsenic, barium, cadmium, chromium, copper, lead, mercury, osmium, selenium, silver etc..(do not mix together, keep each type separate) Mineral acids hydrochloric acid, nitric acid, sulphuric acid, perchloric acid (do not mix together, keep each type of acid in separate container)


Inorganic Bases sodium hydroxide, potassium hydroxide, ammonia (do not mix together, keep each type in separate container) Oxidizers potassium nitrate, hydrogen peroxide,potassium permanganate, bleach (do not mix together, keep all in separate containers) Reactive wastes phosphorus pentoxide, sodium hydride, sodium methoxide, dry picric acid, (do not mix together, keep all in separate containers)


NEVER store the following types of wastes near each other:

Acids and bases. Organics and acids.Cyanide, sulfide or arsenic compounds and acids.Alkali or alkali earth metals, alkyllithiums etc. and aqueous waste.Powdered or reactive metals and combustible materials. Mercury or silver and ammonium containing compounds. If a bottle broke in a waste storage area where incompatibles were present, the results could be disastrous. Remember: incompatible bottles of wastes should be stored in separate cabinets, preferably as far apart as possible!

Self-Auditing Checklist For Hazardous Waste Generators

ALL hazardous waste containers must comply with ALL of the following requirements at ALL TIMES.

1. Is the container sound? (No cracks, rust or deterioration permitted). 2. Is the container compatible with the waste? (No metal cans, in particular). 3. Are the contents of the container compatible with each other? 4. Is the container properly labeled, including the words Hazardous Waste and a date?

Self-Auditing Checklist For Hazardous Waste Generators5. Are the contents of the container clearly

listed? 6. Is the container closed with a properly fitting cap? (Not left with a funnel inserted.) 7. Is the waste container located in the lab (not in a hallway or storeroom)? 8. Is there less than 55 gallons of waste in the laboratory? (yes) 9. Is the waste located away from floor drains or sinks? (yes)10. If the container is full, is it being taken to the waste boot for disposal?

Taking Waste to the Waste Storage Area1. Bring your waste to the waste area or boot.

Make sure that: ALL waste containers MUST have a proper "HAZARDOUS WASTE" label with start date.

Taking Waste to the Waste Storage AreaALL contents are listed

The bottle or jar has a cap that fits tightly. If liquid, there is at least 1" of room at the top of the container. The outside of the bottle is clean and dry.Incompatible wastes are not mixed. Halogenated wastes are separate from "regular" organic wastes whenever possible (it is much more expensive to get rid of halogenated waste)!The pH is known and listed on the disposal tag (yes, even for organic liquids).

Taking Waste to the Waste Storage Area2. Fill out a chemical waste disposal tag. Be sure

to:

Complete all the information requested (yes, this includes pH for ANY waste liquid, including organics). Write out chemical names -- no abbreviations and no chemical formulas (i.e. "Ether" instead of "Et2O" and "Dimethylphosphinoethane" instead of "DMPE"). Give the approximate percentage of each waste component.

Thank You!

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JEFFREY M. STA. INES, Ph.D. Science & Chemistry Education