Laboratory Techniques and Safety: Chemistry Form One studynotes

A laboratory is a room or building specially designed for conducting various scientific experiments. An appropriate school laboratory has the following features:

a room with enough space for carrying out scientific experiments;
a store for keeping laboratory apparatus, chemicals and reagents;
an office for laboratory technician to sit in and design scientific experiments;
enough ventilation to let in fresh air and light;
wide doors and several exits for emergency evacuation in case of an accident; and
a wide table in front of the laboratory room, fitted with sinks for experiment demonstrations by the teacher or technician.

Rules and safety precautions in a chemistry laboratory

Laboratory Rules

Chemistry is best studied through doing experiments. Most experiments are conducted in the laboratory. It is important to read and follow laboratory rules to avoid causing accidents. Your teacher will teach and give you more rules. The following are some important laboratory rules:

Do not enter the laboratory without permission from your teacher or laboratory technician.
Wear safety goggles all the time while in the laboratory. Obey this rule whether you are actually working on an experiment or simply writing in your laboratory notebook.
Contact lenses are not allowed. Even when worn under safety goggles, various fumes may accumulate under the lens and cause serious injuries or blindness.
Put on closed shoes and trousers when in the laboratory. Sandals and shots are strictly prohibited.
Never walk or run unnecessarily in the laboratory.
Tie back long hair when using open flames.
Eating, drinking, and smoking are strictly prohibited in the laboratory.
Don’t perform any experiment not authorized by your teacher or lab technician. If you are curious about trying a procedure not covered in the experimental procedure, consult your teacher or laboratory technician.
Never taste anything. Never directly smell the source of any vapour or gas; instead drift a small sample to your nose. Do not inhale this vapour directly but take in only enough to detect an odour if one exists.
Always wash your hands after experiments.
Never use your hands to transfer chemicals. Use a spatula instead.
Notify your teacher or technician immediately in case of an accident
Know what chemicals you are using, carefully read the label twice before taking anything from the reagent bottle. Do not interchange labels.
Excess reagents are never to be returned to stock bottles. If you take too much, dispose of the excess.
Many common reagents, for example, alcohol, acetone and carbon disulphide are highly flammable. Do not use them anywhere near open flames.
Pour more concentrated solutions into less concentrated solutions to avoid violent reactions. For example, always add acid to water; not water to acid. If you pour water into acid instead, the heat of reaction will cause the water to explode into steam, sometimes violently, and the acid will splash.
If chemicals accidentally splash onto your skin or eyes, flush immediately with plentiful amounts of water and report to your teacher or lab technician.
Never point a test tube or vessel that you are heating at yourself or your colleague.
Dispose of chemicals properly. Unless you are told otherwise, assume that only water may be poured in the laboratory sinks.
When an experiment is completed, always clean up your work area and dispose of the broken glass properly. Return all equipment to its proper storage places.
Never take away anything from the laboratory without your teacher’s permission.
Beware of hot glass because it looks exactly the same as a cold glass. Never touch it with your hand.
Always adjust the Bunsen burner to give a luminous flame when not using it (or just simply turn it off).
Use equipment or apparatus only for its designated use.
Never eat or drink from laboratory glassware.
Make sure all the burners are turned off before leaving the laboratory. Check that the gas tap is off as well.
Never heat a liquid in a closed container. The expanding gases produced may blow the container apart, injuring you or others.
Use only those chemicals needed in the activity. Keep all lids closed when a chemical is not used.
Do not use the same spatula to remove chemicals from two different containers. Each container should have a different spatula.
Replace all stoppers, covers and caps as soon as you finish using it. Be careful not to exchange stoppers from two different containers.
When heating glassware, use wire gauze or ceramic screen. This will protect glassware from the flame of a Bunsen burner.
Never use broken or chipped glassware. If glassware breaks, inform your teacher and dispose of glassware in the litter bin.
Keep all windows open for proper ventilation.
When carrying out the experiment where you expect harmful gases to be produced, use the fume chamber. The fume chamber helps to disperse hazardous gases and vapours safely.
Use a lighter or wooden splint to light burners. Do not use papers. Always strike the match before turning on the gas supply.
In case of a gas leakage, turn off the gas tap and open the windows. Leave the room immediately.
Do not touch any electrical equipment with wet hands. 36. Turn off any gas or water taps that are not in use.

The Safety Measures for a Chemistry Laboratory

The chemistry laboratory can be a place of discovery and learning. However, by the very nature of laboratory work, it can be a place of danger if proper common-sense precautions are not taken. Effort has been made to eliminate the use of explosives, highly toxic and carcinogenic substances from the experiments which you will perform. However, there is a certain unavoidable hazard associated with the use of a variety of chemicals and glassware. You are expected to learn and adhere to all safety guidelines. This will ensure a safe laboratory environment for yourself and the people you may be working with or those near you. The following are important laboratory safety measures to obey:

Label and lock all storage areas, cupboards, drawers, storage cabinets, refrigerators, etc. Locking will prevent accidental contact with chemicals or interference with equipment.
Be familiar with the location, use and limitations of the safety devices. This includes fire extinguishers, fire blankets, fume hood, spill cleanup materials, first aid kit, eyewash stations and fire alarm.
Keep all chemicals in properly labelled containers. This will prevent accidental use of the wrong chemical for a particular experiment.
Be familiar with the appropriate safety measures to take when exposed to different hazardous materials. Information is available from your teacher or laboratory technician.
All chemicals that react with each other must be stored separately.
Be aware of the interaction of laboratory furniture and equipment with chemicals used or stored in the laboratory. For example, oxidizers should not be stored directly on wooden shelves.
Use fume hoods/cupboards/chambers whenever possible.
Never store food in a refrigerator or freezer where hazardous chemicals are stored. Also, do not eat anything you find in the laboratory or in the laboratory freezer or refrigerator.
Make sure fire extinguishers are in good condition. Report any broken seals, damage, low gauge pressure or improper mounting to the teacher or laboratory technician. If the seal has been broken, assume that the fire extinguisher has been used and must be recharged. (Note: Do not use fire extinguishers unless you are trained and feel confident to do so).
Stored chemicals must be inspected regularly to ensure they have not expired. Note the date when bottles were received and when were first opened. Note expiry dates on chemicals and their special storage conditions.
Eliminate safety hazards by maintaining laboratory work areas in a good state of order.
The laboratory must have wide emergency exits and wide windows. Wide exits facilitate easy evacuation in case of emergency. Wide windows allow enough air to enter and circulate in the laboratory. (Note: Maintain at least two clear passages to laboratory exits).
Always keep tables, seats, fume hoods, floors and desks clear of unnecessary material.
All equipment should be inspected before use. In addition, they should be checked regularly to ensure they are safe for use.
If experiments must be left unattended, place a note next to experimental apparatus indicating the chemicals involved, your name and telephone number on which you can be reached in case of an emergency.
Keep the laboratory floor clean and dry at all times. Clean spills of water or chemicals immediately. Then notify other laboratory workers of potential slipping hazards.
The laboratory must be equipped with potable fire extinguishers and other safety devices with clear instructions on how to use them in case of any emergency.
Containers for holding or storing chemicals must be inspected for leakages or other damages. They should have tight stoppers or covers.
All experimenters and other persons working in the laboratory should wear protective gears to minimize exposure to hazards. These gears may include lab coats, hand gloves, gumboots, safety goggles, aprons, etc.
There should be a manual or instruction guides on how to treat spills of different chemical substances.
The fume chamber should be labeled. It should be kept in good condition to minimize unexpected gas leakages or emissions.
Gas cylinders should be labeled, stored properly, and supported. Moreover, they should be in good working conditions all the time.
Each laboratory should be equipped with adequate first aid kits.
Equipment for monitoring contamination should be installed to give alerts of any possible dangers.

NOTE: All the above rules and safety measures are applicable to all research, teaching and academic laboratories. However, your laboratory may require some more rules that apply to specific materials and equipment.

First aid and first aid kit

FIRST AID

First aid is the help given to someone who is injured or sick before the victim gets further medical assistance. This help can be given by any person regardless of his/her knowledge in a medical profession.

Whenever an accident occurs, something must be done immediately to help and save life of the victim. You must always be ready to give a hand to a victim whenever an accident occurs close to you. To give aid effectively and successfully, one must have elementary knowledge on how to assist different victims. If you do not know how to help a certain victim, you can ask someone to assist instead. Do not engage yourself in assisting if you actually do not know where to start. You may find yourself worsening the situation of the victim unknowingly. However, this should not be taken as an excuse for failing to help. Always be ready to render some kind of help. First aid helps to:

relieve pain and bring hope to the victim.
prevent permanent disability
prevent the victim’s condition from getting worse
reduce the possibility of death.
shorten recovery time

Possible Causes of Accidents in a Chemistry Laboratory

Accidents may occur in a school laboratory if utmost care is not taken into account. Accidents in the laboratory are mainly cuts on parts of the body such as hands, fingers, legs or head. Others are burns from flames, scalds from boiling fluids, bruises and grazes due to accidental falling on a slippery floor.

Some possible causes of accidents in the laboratory include:

Failure to follow the correct experimental procedures for example, pouring water into an acid instead of pouring an acid into water as the rule is.
Neglecting some laboratories rules such as ignoring to wear protective gears, tasting the chemicals, eating or drinking while in the laboratory, etc.
Failure to adhere to proper conduct in the laboratory like running unnecessarily and conducting experiments without your teacher’s or technician’s permission and guidance.
Improper use or handling of laboratory equipment and apparatus when conducting experiments, which could lead to breakage and in turn cause cuts, bruises, grazes, etc.
A slippery laboratory floor which can cause fractures, cuts, bruises, grazes, etc
Accidental spillage of chemicals on body parts such as hands, face, eyes, etc, could lead to burns and damage.
Poor ventilation in the laboratory may cause suffocation (due to inadequate oxygen supply) and poisoning (by inhaling poisonous gases produced when experimenting).
Improper disposal of chemical wastes may result in explosions, burns or even fires.
The leaking of gases from taps or cylinders may cause fires or even explosions.
Use of wrong reagents due to incorrect labeling of chemicals or use of reagents or chemicals that have expired may cause burns, poisoning or damage to apparatus or equipment.
Inadequate prior information or knowledge on procedures and hazards associated with certain practical activities or reactants may result in burns, poisoning or explosions.
Loose or improperly plugged electrical appliances may cause electric shock, especially when touched with wet hands and during fixing of sockets.

In general, it can be concluded that most laboratory accidents are a result of negligence and carelessness of experimenters. It is also due to failure to follow the laboratory rules and general safety measures.

The Items Found in a First Aid Kit

A First Aid Kit is a box in which first aid chemicals, tools and instruments are kept. In the laboratory, the box is usually kept in a place where it can be easily reached in case of an accident, preferably on the wall.

Each student must be familiar with the tools and chemicals kept in the kit and learn how to use them to provide first aid to a victim.

First aid kit and its contents

How Each First Aid Kit Item is Used

The table below shows types of chemicals found in a First Aid Kit and their functions.

Tool/chemical/item	Function
First aid manual	Contains guidelines on how to use the items in the first aid kit
Sterile gloves	Worn on hands when attending bleeding cuts or wounds to avoid infecting wounds and to prevent direct contact with the victim’s body fluids
Sterile dressing	Stops bleeding
Antiseptic agent	Cleaning and disinfection of wounds, cuts, bruises, grazes or blisters
Soap	Washing hands, wounds and equipment
Antibiotic ointment	Prevents infection on cuts and bruises in or near the eye
Burn ointment	Applied on burns to prevent infection
Petroleum jelly	Soothing broken skin
Plaster or adhesive bandage	Covering small wounds or cuts
Sterile gauze	Covering wounds to protect them from dirt or germs
Eye wash solution	Flushing the eyes or as a general decontaminant
Thermometer	Recording body temperature
Antibiotic towelettes or cotton wool	Cleaning and drying cuts and wounds
Iodine tincture	Dressing fresh cuts and bruises
Pain relieving drugs such as aspirin, paracetamol, panadol, etc	Relieving mild pains
Liniment	Reducing muscle pain
Mild antibiotics	Treating mild bacterial infections on the skin, ear, nose and mouth
Gentian violet solution	Applied on minor wounds and treatment of serious heat wounds
Hydrogen peroxide solution	Cleaning wounds
Methylated spirit (70% alcohol)	Cleaning cuts and bruises
Bandages	Dressing wounds and cuts, and immobilizing injured limbs
Scissors or razor blade	Cutting dressing materials
Dental kit	Treatment of broken teeth, loss of crown or filling
Safety pins (small and big)	Splinter removal and securing triangular bandage slings
Tweezers	Splinter or stinger removal
Resealable oven bag	Container for contaminated articles
Moleskin	Applied to blisters or hot spots
Triangular bandage	Used as a sling, towel or tourniquet
Boiled, clean water	Washing hands and drinking
Nasal spray decongestant	Nasal congestion from colds or allergies
Torch	Source of light
Whistle	Blown to call for help

Basic chemistry laboratory apparatus and their uses

Instruments used for carrying out different experiments in the laboratory are called laboratory apparatus. Laboratory apparatus can be classified according to their uses as:

apparatus for holding things e.g. test-tube holder, retort stand and clamp, test-tube rack, tongs and tweezers;
apparatus for taking measurements e.g. thermometer, burette, pipette, measuring cylinder, measuring flask, beam balance, electronic balance, common balance, measuring syringe, beaker and stop watch;
apparatus for heating substances e.g. boiling tube, pipeclay triangle, crucible and lid, wire gauze, deflagrating (combustion) spoon, Bunsen burner, spirit lamp, tripod stand, evaporating dish, wire gauze and stove;
apparatus for doing chemical reactions (or testing) e.g. beaker, test tube, dropper, flask, watch glass, gas jar and thistle funnel;
apparatus for filtering e.g. filter funnel, filter paper and cotton wool;
apparatus for grinding e.g. mortar and pestle;
apparatus for storage e.g. reagent bottles and wash bottle;
apparatus for scooping e.g. spatula; and
apparatus for safety e.g. goggles and hand gloves.

The Apparatus Used in a Chemistry Laboratory

List the apparatus used in a chemistry laboratory

Some chemistry laboratory apparatus

	Apparatus	Material	Uses
1.	Test tube	Glass	Holding chemicals or, heating substances
2.	Funnel	Glass or plastic	Leading liquids into containers, and for filtration purposes
3.	Beaker	Glass or plastic	Holding, heating, and mixing liquids
4.	Flask	Glass	Holding, heating, and titrations
5.	Retort stand	Metal (iron)	Holding apparatus during heating
6.	Tripod stand	Metal (iron)	Holding apparatus during experiments
7.	Gas jar	Glass	Gas collection
8.	Wash bottle	Plastic	Washing
9	Crucible	Ceramic or non-reactive metal	Heating
10	Test tube holder	Metal and plastic or wood	Holding test tubes while heating
11.	Weighing balance	Metal and plastic	Measuring weight (or mass)
12.	Spatula	Metal	Scooping small quantities of powder or crystalline chemicals
13.	Condenser	Glass	Cooling hot liquids
14.	Pipette	Glass	Accurate measurement of specific volumes of liquids for titrations
15.	Burette	Glass	Titrations
16.	Trough	Glass	Assists in gas collection
17.	Tongs	Metal	Picking and holding hot substances and apparatus
18.	Measuring jar	Glass	Measuring volumes of liquids
19.	Thistle funnel	Glass	Leading liquids into containers and apparatus
20.	Dropper	Glass and rubber	Dropping indicators into reagents
21.	Mortar and pestle	Clay	Crushing or grinding substances
22.	Wire gauze	Metal	Even distribution of heat during heating
23.	Spring balance	Metal	Measuring weight
24.	Distillation flask	Glass	Distillation
25.	Combustion spoon	Metal	Burning powder in jars
26.	Thermometer	Glass and liquid metal	Measuring temperature
27.	Delivery tube	Glass	Allowing gases pass through
28.	Bunsen burner	Metal	Heating substances
29.	Separating funnel	Glass	Separation of immiscible liquid mixtures
30.	Measuring cylinder	Glass or plastic	Measuring volumes of liquids
31.	Measuring syringe	Plastic	Sucking in and measuring specific volumes of liquids
32.	Stopwatch	Plastic or glass and metal	Accurate measurement of time
33.	Watch glass	Glass	Used as a surface to evaporate some liquids, to hold substances being weighed or observed, or as a cover for a beaker
34.	Boiling tube	Glass	Is a large test tube used to heat substances requiring strong heating, or when the sample is too large for a test tube
35.	Evaporating dish	Ceramic	Heating and evaporating liquids and solutions
36.	Filter paper	Paper	Filtration
37.	Test tube rack	Wood or plastic	Placing test tubes
38.	Reagent bottle	Glass	Storing different chemicals
39.	Wash bottle	Plastic	Storing distilled water
40.	Safety goggles	Glass	Protecting eyes from chemical spills, strong light and harmful vapours
41.	Bell jar	Glass	Keeping gases, moisture, air, etc. or creating vacuums

Chemistry Laboratory Apparatus According to their Uses

Categorize chemistry laboratory apparatus according to their uses

The apparatus can also be classified based on materials they are made of. Most of the apparatus are made of glass. Others are made of metal, plastic or wood. Just a few are made of clay and asbestos.

Table summarizes some common laboratory apparatus and their uses.

Composition and uses of some chemistry laboratory apparatus

Common Chemistry Laboratory Apparatus

Use common chemistry laboratory apparatus

Common laboratory apparatus

Activity 1

Your teacher will guide you how to measure the volume of liquids using the other apparatuses.

Aim: To measure volume of liquids using different apparatus

Materials: pipettes, burettes, measuring cylinders, water, beakers.

Procedure

Pour some water into a graduated measuring cylinder with a capacity of 100 cm³. Add the water, one drop at time, up to a 25-cm³mark.
While adding water, position yourself at eye-level with the mark on the cylinder. This will enable you to obtain the most accurate measurement. To simplify the work of reading the level of the water, you may use coloured water.
Select a volumetric flask measuring 50 cm³. Pour the water into the flask until it reaches the mark on the flask’s neck.
Position yourself at eye-level with the mark. You will obtain the most accurate reading when the mark appears straight rather than elliptical. To obtain this, put a flask on a flat table.
Add water one drop at a time. Do so until the bottom of the curved surface of the water exactly matches the mark on the flask.

Activity 1.2

Aim: To measure the masses of solid substances

Materials: chemical, electronic or spring balance, watch glasses, various substances such as sand, sugar, salt, flour, stones, fruits.

Procedure

Put an empty watch glass on the weighing balance. Note down its mass. Record this as mass M₁.
Place the various items you have on the watch glass, one item at a time. Note down the mass. Record this as M₂.

Note: to obtain the mass of an object, we subtract the mass of an empty watch glass from the mass of the watch glass and the substance. That is, M₂ – M₁.

For example

Warning signs

Chemical warning signs are safety symbols found on containers, especially those used in the laboratory. The symbols are also found on tanks or containers that are used to carry, store or transport certain chemicals. Containers holding flammable fuels such diesel, petrol and natural gas, as well as those containing toxic chemicals normally bear warning symbols. These symbols indicate the danger (hazard) likely to be caused by the chemicals they contain if carelessly handled.

When performing experiments in the laboratory it is important to read the safety signs on chemical containers. This will minimize the chances of causing accidents in the laboratory.

The Basic Chemical Warning Signs

Draw and label the basic chemical warning signs

Some chemical warning signs

The Concept of Warning Signs

Explain the concept of warning signs

Before conducting any experiment in the laboratory you must be aware whether the chemical you want to use is toxic, corrosive, flammable, oxidant, explosive or harmful. This information will help you know how to handle the chemicals safely. Proper handling of chemicals enables you avoid unnecessary accidents. Below is an explanation pertaining to some hazard labels represented by the symbols above.

Toxic

Toxic substances include those that can poison you or the other person working close to you in the laboratory. These substances can kill within a short time or after some few days. They should not be allowed to get into your body through body orifices (month, nose, eyes, ears, etc). Neither should they be allowed to contact your skin. They become even more dangerous when they get into the body. If it happens that these substances touch your skin accidentally, wash it immediately with ample water.

Corrosive

Corrosive substances refer to those chemicals that can burn or corrode (eat away) your skin. They can also corrode wood or metals. One can become blind if such substances accidentally get into his/her eyes. If they contact your skin, wash it immediately with a lot of water. Examples of corrosive substances commonly found in a school laboratory are concentrated mineral acids such as sulphuric acid, hydrochloric acid and nitric acid, and concentrated alkalis such as sodium hydroxide, potassium hydroxide and ammonia.

Flammable

These chemicals catch fire easily. For this case, they should be kept away from flames or fires. They can be set into fire by any kind of sparks, be it from welding or fire. When working with flammable chemicals in the laboratory all burners must be put off. These chemicals are usually very volatile. The containers used to carry them must be stoppered immediately after every use. Examples of flammable chemicals are methylated spirit, ether, acetone and methanol.

Explosive

Explosive chemicals are those that explode rapidly upon detonation (set into fire or ignited). Because the reaction is rapid, it results into throwing off particles at a high speed. For this reason, they should not be kept in glass containers. This is because during explosion the particles will disperse around and cause serious injuries to people. Those explosive chemicals that can react without external detonation are even more dangerous

Oxidizing agents

These chemicals can stimulate a burning substance to burn efficiently and faster. Therefore, they must be kept away from fires no matter how small that fire may be. An example of oxidizing agent is oxygen gas.

Harmful or irritant

Harmful substances are those that can impair your health or make you fall sick. They do not normally kill instantly but have detrimental effects following a long exposure to them. These chemicals do not kill immediately. However, care must be taken when handling or dealing with them. Irritating substances cause pains when in contact with the body. They are dangerous to health when in contact with the body surface for a long period of time.