Chemical hazards are 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.

Common chemical hazards include:

Fire hazards
Explosions hazards
Extremely toxic chemicals
Lachrymators (substances that irritate the eyes and produce tears)
Vesicants (substances that can blister and burn body tissues by contact with the skin or inhalation)
Carcinogens (substances that produce cancer)

List any four precautions against biological hazards during specimen collection

Wear protective clothing when handling lab animals and plants.
Clean or disinfect tables using methylated spirit before and after experiments.
Incinerate used materials as soon as possible.
Use protective clothing only in the lab and never use it outside the laboratory –leave them in the laboratory.
Never smoke or eat anything in the laboratory.
Do not store any material in a food refrigerator or mix with other food utensils.
Wash your hands thoroughly with an appropriate antiseptic after every practical.
Avoid body contact with laboratory animals and plants.
Ensure maximum care when handling and storing carcinogenic chemicals.
Stock of fresh animals must be obtained from a reliable source. infected animals should never be used for any practical

Commonly used solvents such as ether, dioxane and THF can form explosive peroxides after exposure to air. What can be done to minimize the hazards associated with peroxidizable compounds?
- Date and label when initially opening the container.
- Store the compound in an obvious location where it will not be forgotten.
- Check ether solvents and other peroxides formers for peroxides six months after opening the containers and every six months thereafter or dispose of them.
Mercury vapor is highly toxic and mercury spills are very difficult to clean up because the mercury breaks into microscopic balls which roll into cracks and crevices where they cannot be easily seen or removed. What can be done to reduce the chance of mercury spills?

Use a catch pan of appropriate size and depth under all mercury- containing equipment.
Use non-mercury-containing thermometers where possible.
Never use a mercury thermometer in a heated oven.

How should spilled mercury be cleaned up?

Mercury droplets can be amalgamated with calcium polysulfide, zinc dust, sulfur powder or Merconvap for spill clean-up. Aspiration of mercury droplets into a suction flask should be used to remove all visible mercury. The flask can then be taken to a hazardous waste collection site. While coating of mercury with flowers of sulfur temporarily lowers vapor pressure, vibration loosens the HgS coating, and equilibrium pressure is reestablished. Thorough room ventilation may keep total vapor loading down; the best approach is to use all mercury over a catch pan to prevent spills in the first place. The Environmental Health and Safety Office at 777-2211 can assist in clean up and will monitor for mercury vapor.

Teflon, a common component of lab supplies (e.g. containers, tubing, and stir bars) is considered inert in most circumstances, but what common substance can react explosively with Teflon at elevated temperatures?

Potassium metal.

In the event of a small solvent or corrosive liquid spill which you can clean up yourself, explain the four steps for cleaning up spills.

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 999. Wear appropriate personal protective equipment when cleaning up the spill .
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.
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.
Neutralize the spill

Procedure for neutralizing most inorganic acid spill materials:

1 Slowly add the beaker content to a large volume of cold water (approximately a 1:10 dilution). Never add water to acid, this causes excessive generation of heat in a very localized area and may result in an explosion (especially in the case of sulfuric acid).
Check pH. If neutral, skip step 3 and proceed to step 4.
Slowly and carefully add Na2CO3 (sodium carbonate) or NaHCO3 (sodium bicarbonate) until neutralization is complete.
Decant the liquid down the drain with at least 50 times its volume of cold running water.
Discard the solid as regular waste (except chromic acid.

Procedure for neutralizing most inorganic base spill materials:

Slowly add the caustic spill materials to a large volume of ice water with stirring (approximately a 1:10 dilution).
Add 5% hydrochloric acid until neutralization is complete.
Check with pH paper.
Decant the liquid down the drain with at least fifty times its volume of cold running water.
Discard the solid as regular waste.

State the color coding of each of the following gases in the lab

The colour coding identifies the property of the gas inside the cylinder.

For the purpose of easy identification and the shoulder colours can refer to the gas inside the cylinder. Some typical examples are:

Maroon – acetylene
Grey – carbon dioxide
Brown-helium
Red – hydrogen
Blue – Nitrous oxide
Black – nitrogen
White – oxidant.

Explain why smoking should be avoided while carrying out the following operations:
1. When charging a lead acid battery

Lead acid battery charging is a process that is known to involve release of flammable gases that can ignite fire hence smoking must be avoided

When extracting chlorophyll from spinach leaves using hot acetone

Acetone used as a solvent in this process is an extremely flammable substance with very low flash point temperature hence can ignite if exposed to fire source e.g. by smoking nearby

State the precautions taken when heating a substance in a test-tube.

Heating should be done holding the test tube using test tube holder and should be heated when it is tilted away from one self or away from colleagues

Explain each of the following
1. Botanical hazards

These are specific infections from microorganisms e.g. algae, fungi, bacteria, virus and protozoan and plants e.g. Datura. These plants have alkaloid substances, which are very poisonous .Plants, transmit their infection through ingestion, skin and nose

Zoological hazards

These are infections caused as a result of poor handling of laboratory animals e.g. worms, rabies, chicken pox etc. Animals transmit them through bites stings and scratches.

.Discribe how to use a Co₂fire extinguisher
- Remove the cylinder from the wall
- Hold it in its upright position
- Remove the safety pin
- Aim the nozzle at the base of the fire
- Press the knob
- Try to isolate the fire
Explain why water fire extinguisher cannot be not be used in extinguishing most classes of fires except class A fires.

Because water is in most cases not soluble with organic flammable substanes eg petroleum , not compatible with most combustible metals and also is very hazardous if in contact with electricity fire.

Explain why it is dangerous to direct a jet of compressed air on the skin

Jet of compressed gas have potention to cut , injure or cause rapid cooling on the affected part of skin . this can also supress blood circulation on the exposed part of the skin

Outline the safety precautins to be taken while boring cork to insert glass tubings

Lubricate the end of the glass tubing with a few drops of water, washing-up liquid, glycerol, or vegetable oil.
Hold the glass tubing close to where it enters the hole in the rubber stopper. Protect your hands with work gloves or pieces of cloth (one method is to insert a cork borer (one size above the OD of the tubing) into the hole. The stopper is flexible enough to allow the cork borer to slide right in. Insert the glass tubing and position it appropriately. Then pull the borer back out. The glass tubing will stay in).
Ease the tubing into the hole with a gentle twisting motion. Push the tubing through the hole as far as is required. Do not use force!
Wipe excess lubricating material from the tubing before continuing with the experiment.
If the glass tubing is to be removed from the stopper, it should be done immediately after the experiment is completed.

State the safety precautions that should be taken before evacuating a desiccator and vacuum filtration apparatus

Desiccators and vacuum filtration apparatus have negative pressure, which can cause their collapsing of through sucking in of air. Such items require to be opened slowly and carefully until when their internal and external pressure are at equilibrium

Discuss safety with respect to
1. Storage of gas cylinders

Cylinders must be kept cool, and should be protected from sunlight, rain, frost, wet soil and corrosive conditions. If cylinders have to stand in the open, they should be protected from the rays of the sun.

b.valves and fitting of gas cylinders

Carefully open all valves, slowly, pointed away from you and others, using the proper tools. Close all valves when cylinders are not in use. Never tamper with safety devices in cylinders, valves or equipment. Do not allow flames to contact cylinders and do not strike an electric arc on cylinders.

Explain three types of hazards caused by leakage of gas in the laboratory.

Risk of causing fires and explosions if exposed to a naked flame
Risk of displacing oxygen if leakage is in a poorly ventilated environment. This can lead to suffocation, unconsciousness, and lack of concentration
Risk of causing oxidation reactions if leaked oxygen gas it gain contact with reactive metals
Risk of encouraging growth of pathogenic aerobic bacterial if the leaking gas is oxygen

Identify the hazard symbols below

Outline the process of responding to spill of hazardous material in the laboratory

Collect the material used to contain or neutralize the spill, and dispose of it in the specified manner. If the spill is small, that may be a plastic bag, while larger spills may require plastic pails or drums. In some cases, you’ll also need to dispose of any equipment such as brooms or dustpans that you used to clean up the material. If what you’ve gathered qualifies as a hazardous material, be sure to label it accordingly and dispose of it as specified by local laws and environmental regulations.
Clean the surfaces that were affected by the spill with the correct material, whether that’s bleach, a mild detergent, water, or some other material appropriate for the material that was spilled. Instead of rinsing the area after cleaning, you may need to use another method such as more absorbent material.
Be sure to wash your hands and any other areas that may have come in contact with the materials thoroughly. If your clothing can be safely decontaminated and cleaned, follow the appropriate steps. Otherwise, dispose of the clothing following proper safety procedures. laboratory

Describe decontamination process of a laboratory worker when leaving a radioactive laboratory

i Remove outer layer of clothing.

Take off your outer layer of clothing: Taking off your outer layer of clothing can remove up to 90% of radioactive material.

Be very careful in removing your clothing to prevent radioactive dust from shaking loose. Put the clothing in a plastic bag or other sealable container and put the bag in an out-of-the-way place, away from other people and pets.

ii.Wash yourself off.

Wash your hands, face, and parts of your body that were uncovered at a sink or faucet. Use soap and plenty of water.

If you do not have access to a sink or faucet, use a moist wipe, clean wet cloth, or a damp paper towel to wipe the parts of your body that were uncovered. Pay special attention to your hands and face.

Gently blow your nose, wipe your eyelids, eyelashes, and ears with a moist wipe, clean wet cloth, or a damp paper towel.

Put the used wipes, cloth or towel in a plastic bag or other sealable container and place the bag in an out-of-the-way place, away from other people and pets.

iii.Put on clean clothes

If you do not have clean clothes, take off your outer layer of clothing, shake or brush off your clothes taking care to cover your nose and mouth, and put your clothes back on.

Describe proper protection methods against radiation hazards

Using Pocket dosimeters are used to provide the wearer with an immediate reading of his or her exposure to x-rays and gamma rays. As the name implies, they are commonly worn in the pocket.
Using film badge . this consists of two parts: photographic film and the film holder. The silver film emulsion is sensitive to radiation and forms the latent image in the film. Once developed, exposed areas increase in optical density (film blackening) in response to incident radiation.
Lead aprons or vests.- Wearing lead aprons can reduce a worker’s radiation dose.
Lead thyroid collar. A lead thyroid collar offers additional radiation protection for the thyroid (a gland located in front of the neck) that is particularly sensitive to radiation.
Lead gloves. Lead-lined gloves offer some protection for workers from radiation exposure to the hands and should be used for some X-ray equipment if hands must be placed in the direct X-ray field.
Safety goggles. Leaded eye wear (lead glasses or radiation glasses) or opaque safety goggles can protect a worker’s eyes from radiation exposure.

Define the term’ dose’ as used as used in radiation

it is the energy of ionizing radiation absorbed per unit mass of any material

Describe any types of monitors used to measure radiations

Radiation survey meters (e.g., Geiger Muller and similar devices) detect radiation in real time
Personal dosimeters
Film badges do NOT provide information in real time, but they can detect prior radiation exposure if the device was worn at the time of exposure.
Self-reading personal dosimeters can provide real time information about exposure, with or without alarms reporting accumulated dose or dose rate. For information about capabilities of various kinds of personal dosimeters,

State the precaution that should be taken when
1. Diluting mineral acids to the required concentration

Wear appropriate skin and eye protection
Always dilute by adding acids to water
Dilute and mix slowl

(b).clamping a burette glass tap

Avoid using excessive force when clamping and ensuring that it is firmly fixed on the stand

Inoculating nutrient agar in a Petri dish

Putting on appropriate protective clothing e.g. gloves
Ensuring that the inoculating is properly sterilized by flaming before and after inoculation
Not touching or putting anything in the mouth during inoculation and washing hands after experiment
Working the experiment in a biological safety cabinet

Glass articles in glass blowing room

Special Hand protection gloves
Eye goggles – used for the safety of the eyes
Face masks
1. Microorganism in biomedical lab
Hand gloves
Face masks
Lab coats

During a practical session, a lighted Bunsen burner fall in a waste paper basket causing it to catch fire.
- Explain what should be done to contain this fire

Do not create panic.
Immediately try to safely evacuate the students from the fire risk area.
Try slowing down the spread of fire by separating burning materials from other unburnt combustible materials around
Using the fire blanket cover the burning either items or spray the area using water or CO₂fire extinguisher.
Instruct that all doors and windows to be closed to rid of oxygen supply from the room. Raise the alarm for everybody to run to the fire assembly point where the roll call will be taken. Can call the local fire fighters if fire will run out of control

Explain the three requirements necessary for a fire to burn.

Fire is simply heat +light that is evolved during a chemical reaction called combustion .It relies upon the presence of oxygen from the air reacting with flammables.

Draw al labeled diagram of a fire triangle

The combination of oxygen, fuel, and heat source provides three basic components of combustion that can be represented as a fire triangle

Classify fire into its suitable classes of fire giving their appropriate type of fire extinguishers
1. Class A fire

They are fires caused by solid organic carbonaceous materials e.g. wood, paper, textiles, etc.
The most appropriate fire extinguishers to be used for this type of fires include; Water,CO₂, foam, dry powder etc.
1. Class B fire
They are fires caused by liquids or easily melted solid organic compounds e.g. petrol, ethanol, plastics etc.
The most appropriate fire extinguishers to be used for this type of fires include; CO₂, Foam, dry powder but not water
1. Class C fire
They are fires caused by flammable gases e.g. petroleum gases
The most appropriate fire extinguishers to be used for this type of fires include; CO_2,Foam and dry powder
1. Class D fire
They are fires caused by Metals e.g. Na, Mg etc.
The most appropriate fire extinguishers to be used for this type of fires include; Dry powder, C0₂
1. Class E fires
They are fires caused by electric faults
The most appropriate fire extinguishers to be used for this type of fires include; CO₂, dry powder but not water.

Describe how to use a fire extinguisher to extinguish class B fire

Carbon dioxide extinguishers do not leave any residue, unlike a foam extinguisher. They can also be used on Class B fires, those involving flammable liquids such paraffin or petrol. CO2 extinguishers work by smothering the fire and cutting off the supply of air.Carbon Dioxide Extinguishers (CO2) have a black label.

Pull out the safety pin to activate the fire extinguisher.
Aim the nozzle down low towards the base of the fire from a safe distance away.
Squeeze the operating lever to discharge the extinguisher. This will look different depending on the type of extinguisher.
Sweep the nozzle from side to side until the fire is extinguished. Carefully step towards the fire area as it goes out to avoid any potential reignition.

Equipment that produces high current or high voltage poses a special hazard in many research labs. As a general warning of the dangers, equipment using high currents or high voltages must be clearly marked and rooms containing this equipment in use should have warning signs at the entrance doorways. List additional precautions that must be taken to minimize personal risks when using this equipment.
- Use a 3-prong plug for proper grounding unless other grounding provisions are made and checked.
- Work with only one hand while keeping your other hand at your side or in your pocket, away from all conducting materials. This prevents accidents resulting from current passing through the chest cavity.
- Avoid becoming grounded by staying at least six inches away from all metal materials including walls and water.
- If you design and build your own equipment be sure to plan for proper shielding to be purchased and/or constructed around your equipment to produce a safe lab environment
Cryogenic liquids pose a unique hazard in the research laboratory due to their extremely cold temperatures and ability to displace oxygen when vaporized in a confined space. Serious injury or death can result from improper use and storage of these liquids. List two common cryogens used in the lab and describe how they should be properly stored?

The two most common cryogens are liquid nitrogen and liquid helium. Both are unreactive and inert. But their low—temperature properties make them substances with which we must take serious precautions. Helium should be stored in the helium dewar; nitrogen goes into the nitrogen dewar. Do not mix the two, and do not put ANYTHING else in either dewar

List five important safety precautions that must be followed when transferring cryogenic materials.
- Use gloves to protect your skin.
- Do not tuck your TROUSER into your shoes or boots!If a cryogen momentarily collects around your foot, you will not be able to get your shoes off fast enough to prevent damage to your skin.
- Use low pressures (2-4 psi) when transferring liquid helium. High pressures (10 psi) in transfer is both dangerous and wasteful.
- Do NOT leave your dewar pressurized at anytime after completing the transfer. Always open the pressure release valve.
- Maintain adequate ventilation in the lab when using and transferring a cryogen. Areas suspected of being oxygen deficient due to the release of large quantities of cryogenic vapor should be evacuated immediately and further access to the area prevented until area is determined to be safe.
List at least three safety considerations that you need to follow before using any cryogenic instrumentation and/or equipment.
- Make sure that cryogenic equipment has a working pressure relief valve.
- Make sure that the pressure relief device is configured such that if it is actuated that the flow of gas does not present a danger to the operator or other lab equipment.
- Vacuum integrity must be maintained at all times. Cryogenic equipment must be kept clean.
A good electrical ground protects you by giving the electrical current a safe path to follow in the case of an equipment failure or fault. List at least three common situationsthat can result in a piece of equipment having a bad electrical ground?

Using 2-prong plugs instead of 3-prong plugs.
Using a 3-prong plug adapter in a 2-prong outlet.
Using the equipment with wires that are bare of insulation.
Using the equipment with wires that are broken.

General electrical safety includes the proper use of outlets, extension cords and outlet strips. Which of the following situation(s) describe unsafe practices in the use of outlets, extension cords or outlet strips.
1. Placing one or more extension cords along the floor in areas where people may trip over them.
2. Plugging too many pieces of equipment into the same outlet.

Using extension cords that aren’t rated to carry the current required by a piece of equipment.

All of the above represent unsafe laboratory situations which could result in fire, accident and /or electrocution. Constant surveillance of the research lab electrical utilities is mandatory to insure a safe work area for all lab personnel.

Identify four types of faults on electric plug that can lead to accidents in the laboratory

Electric shock
Burns from contact with live parts.
Injury from exposure to arcing, fire from faulty electrical equipment or installations.
Explosion caused by unsuitable electrical apparatus or static electricity igniting flammable vapours or dusts, for example in a spray paint booth.

State any four safety precautions that should be taken before evacuating air from a desiccator

The cover of the desiccator is usually sealed to its body with a thin layer of silicone grease. This forms an airtight seal and requires precaution in opening the cover and putting it back.

Slide cover horizontally with a gentle force until it starts moving. Grasp the knob with one hand and with the other hold the base and apply more force to take it off completely
Do not get tempted to lift the desiccator by lifting the top knob. Always lift with both hands holding the bottom and the cover.
To close place lid gently on top and close slowly by applying a mild force till it closes. Rotate lid gently in both directions to ensure an airtight seal.
Ensure that the rim does not run out of grease but at same time do not use an excessive amount of grease. A thin uniform film is usually sufficient.
Keep the lid upside down on removal but away from the workbench edge to prevent rollover
Place a hot substance carefully inside after removal from the hot air oven. Keep the crucible with the lift ajar for a couple of minutes and then close the lid by sliding it to expel hot air so that the lid does not get blown out due to expansion of hot air and also prevent vacuum formation later which can make opening difficult.
Opening a Vacuum-Sealed Desiccator
When applying a vacuum take care not to exceed the prescribed limit as it can risk an implosion. Gradually open stop- cock on top to release the vacuum inside at time of opening. Try sliding the lid. If there is difficulty in sliding make use of a thin spatula carefully to create a rift between the lid and the body. On hearing a hissing sound of vacuum release slide the top cover by holding the bottom firmly with the other hand.

A desiccator can be used routinely for storage of moisture sensitive compounds, standards and for applications requiring weighing to constant weight. However, storage of materials that are highly reactive with water such as sodium metal is not recommended as on coming in contact with humid air on opening it can lead to violent reaction.

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