Home CHEMISTRY TOPIC 2: LABORATORY TECHNIQUES AND SAFETY | CHEMISTRY FORM 1

TOPIC 2: LABORATORY TECHNIQUES AND SAFETY | CHEMISTRY FORM 1

November 4, 2020

2214

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

State 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

Explain 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 labelled. It should be kept in good condition to minimize unexpected gas leakages or emissions.
Gas
cylinders should be labelled, 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

Identify 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

Name 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

Demonstrate 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

The Items in a First Aid kit to Provide First Aid to an Accident Victim

Use the items in a first aid kit to provide first aid to an accident victim

First aid procedures

Sometimes
accidents may occur in the laboratory due to some reasons or the other.
Whenever an accident occurs, one must be ready and prepared to assist.
The following are some of the health problems that may require first aid
and the procedure to follow when providing help.

Bleeding

Bleeding
is the loss of blood from the body and usually occurs from a visible
wound. Bleeding may be external or internal. It may from artery, vein or
capillary. Bleeding may be severe or light. Excessive loss of blood may
cause death.

(a) Internal bleeding

Signs and symptoms of internal bleeding include the following:

Bruised, swollen, tender or rigid abdomen
Bruises on chest, neck, legs or signs of fractured ribs
Vomiting or coughing up blood.
Wounds that have penetrated the skull, chest or abdomen
Bleeding from body cavities such as the ears, nose, rectum or vagina
Abdominal pulse and difficulty breathing
Cool, moist skin
Fractures

Procedure

First
aid in the field for internal bleeding is limited. If the injury
appears to be a simple bruise, apply cold packs to slow down the
bleeding, relieve pain and reduce swelling.
If you suspect more
severe internal bleeding, carefully monitor the patient. Be prepared to
administer CPR if required (and you are trained to do so).
Seek medical advice immediately if the situation seems to be worse.

(b) Severe bleeding

Procedure

Severe
bleeding with blood oozing out rapidly must be stopped at once. This
can be done by applying direct pressure to the wound. Use a dressing if
available. If it is not available, use a rag, towel, piece of clothing
or your fingers alone. If the wound is large, press the edges of the
wound together but firmly. However, this should be done only if there is
no fracture.
Lay the victim down in a comfortable position.
If
the wound is on a limb, and provided it is not fractured, raise the
wound above the level of the heart. Then continue to apply direct
pressure. This should be done only if bleeding continues and if it does
not cause pain.
If bleeding still cannot be controlled, the next step is to apply pressure at a pressure point.
For wounds of the arms or hands, pressure points are located on the
inside of the wrist (radial artery-where a pulse is checked) or on the
inside of the upper arm (brachial artery). For wounds of the legs, the
pressure point is at the crease in the groin (femoral artery).
When
bleeding stops, clean the wound carefully and thoroughly with a
suitable disinfectant. Do not remove any objects stuck in the wound, as
this would lead to more bleeding.
Place sterile gauze on the
wound and press it down firmly. Cover it with a soft material and hold
it in position using a firm bandage. After the bandage is in place, it
is important to check the pulse to make sure blood circulation is not
interrupted. A slow pulse rate, or bluish fingertips or toes signal a
bandage may be hindering blood circulation.
Seek medical help immediately.

Important:
Once pressure is applied, keep it in place. If dressings become soaked
with blood, apply new dressings over the old dressings. The less a
bleeding wound is disturbed, the easier it will be to stop the bleeding.

(c) Light bleeding

Procedure

Place the victim in a comfortable resting position.
Elevate
the injured part while applying pressure. This should be done only if
the wound is on a limb and you do not suspect a fracture.
Gently and thoroughly clean the wound using water and antiseptic or common salt solution.
Cover the wound with sterile gauze or clean dressing dipped in iodine solution.
Dress and bandage the wound
Take the victim to hospital if bleeding still continues.

(d) Nose bleeding

Bleeding
usually occurs near the tip of the nose. The bleeding may be a result
of high blood pressure, rheumatic fever, or injury. Nose bleeding is
also likely to occur at high altitude because of low atmospheric
pressure or extreme coldness.

nose-bleeding victim

Procedure

Let the victim sit calmly. This makes the heartbeat to slow down and hence reduce bleeding.
Loosen clothing around the neck and chest.
Let
the victim sit upright and lean the head forward slightly. By remaining
upright, the victim reduces the blood pressure in the veins of his or
her nose. This discourages further bleeding. Leaning forward will help
the victim avoid swallowing blood, which can irritate his or her
stomach.
Have the victim pinch his or her nose, to keep nostrils
shut, using thumb and index finger. Ask the victim to breath through
the mouth. Let him or her continue pinching for a few minutes.
Apply cold, wet compression over the nose, face and at the back of the victim’s neck.
When bleeding stops, gently clean the nostrils.
If bleeding does not stop after 20 minutes, take the victim to the hospital immediately.
To prevent re-bleeding after bleeding has stopped:
Ask the victim not to pick or blow the nose and not to bend down until several hours after bleeding.
Let the victim keep his/her head higher than the level of his/her heart.
If re-bleeding occurs:
Ask
the victim to blow out forcefully to clear the nose of blood clots.
Spray both sides of the nose with decongestant nasal spray.
Pinch the nose as described above and seek medical help.

nose-bleeding victim with his head leaned forward.

Suffocation

Suffocation
is a condition in which the lungs are not getting enough oxygen,
causing difficulty in breathing. In such cases, foams can also appear in
the mouth and nostrils. If suffocation is complete (no air at all
reaches the lungs), the lack of oxygen and excess carbon dioxide in the
blood will cause immediate loss of consciousness. Though the heart
continues to beat briefly, death will follow in a matter of minutes
unless emergency measures are taken to get breathing started.

Suffocation
can be caused by drowning, electric shock, gas or smoke poisoning,
choking, asthma, severe infections of the throat or other causes.

Procedure

Remove the cause of suffocation or remove the victim from the cause of suffocation. Loosen tight clothing around the neck.
Make
sure the victim’s airway is open for air to reach the lungs. This can
be achieved by laying the victim on his or her back. Then, with one hand
on the victim’s forehead and the other on the chin, tilt the head
backwards, to open the airway. Tilt the head until the chin points
straight upwards. If the airway is blocked by fluid or solid, remove it.
Administer cardiopulmonary resuscitation (CPR).
This involves blowing air into the victim’s mouth (mouth-to-mouth
breathing). To do this, pinch the nose and close up the mouth. Take a
deep breath and then blow hard into the victim’s mouth. Watch the rise
in chest and repeat the procedure until the victim’s breathing is
restored. In case the person does not respond, go for chest
compressions.
Compressions can be done by placing the palm of
one hand in the space between the nipples and the other hand over it and
pushing the chest by using your upper body weight. Care should be taken
to prevent chest injury or fracture. Two compressions can be given
every second or hundred per minute. After thirty compressions, go for
mouth breathing again. Repeat the procedure until natural breathing is
restored.
Keep the casualty warm using a light blanket.
Take the casualty to the hospital immediately.

figure.

Choking

Choking
occurs when food or a foreign object blocks the upper part of the
windpipe. This interferes with normal breathing. The signs of this
problem include difficulty in breathing and speaking. Have you ever been
with a person who is chocking? Did you know what to do?

When attending a person who is chocking, first notice whether the person can talk, breathe or cough. Caution: Do not try to slap the person on the back. The slapping may only cause the food to become more deeply lodged in the airway.

Procedure

Ask the victim to cough up the object.
If the object remains stuck, give firm but gentle taps between the shoulder plates.
If the object is still stuck, apply quick abdominal thrusts i.e. Heimlich manoeuvre as follows:
Stand behind the victim and make him or her lean forward slightly.
Put
your arms around the person, placing your fist just below the
breastbone. Grasp your fist with the other hand near the top of the
victim’s stomach.
Press your fist onto the victim’s abdomen. Give a series of quick, sharp upward and inward thrusts to dislodge the object.

Thrusting to dislodge the object

Poisoning

A
poison is any substance that can harm the body or seriously endanger
health when taken into the body. A poison may get into the body through
inhaling, swallowing, wounds or skin cuts or absorbed into the body in
other ways. Potential poisons include poisonous fumes (or gases),
laboratory chemicals or even medical drugs and medicines.

In
every household, there are different kinds of things that are
poisonous. Some are deadly even on a very small dose. Others may be more
or less harmless when taken in small quantities.

Examples of poisonous substances at home are kerosene, disinfectants, paints, medicines, artificial fertilizers, etc.

Some
signs and symptoms of poisoning are nausea, vomiting, abdominal cramps,
pain, difficulty breathing, diarrhea, and abnormal skin colour. Others
are breath that smells like the chemicals, chemical burns, empty
medication bottles or scattered pills, sleepiness, confusion or other
unexpected signs.

Procedure

Call
for medical help immediately if the person shows one or some of the
following signs: drowsy or unconscious; having difficulty breathing or
has stopped breathing; uncontrollably restless or agitated.
For the time being, find out what caused the poisoning, i.e. look for the poison and identify it.
If
the person has been exposed to poisonous fumes such as carbon monoxide,
get him or her to where there is fresh air immediately.
If the poison is in the eye:
Wash the eye with a lot of clean water.
Ask the victim to blink as much as possible.
Do not rub the eye.
If the person swallowed the poison:
Remove anything remaining in the mouth
Induce
vomiting if the poison is not strong acid or alkali as these are
corrosive substances. Non- corrosive substances include medicines and
soaps. Vomiting can be induced by inserting your finger in the victim’s
throat until the finger touches the epiglottis.
Do not induce
vomiting if the poison swallowed is corrosive. Corrosive substances
include kerosene, bleach, detergent, laboratory acid, disinfectant or
certain toiletries. If the suspected poison is a household cleaner or
other chemical, read the label and follow instructions for handling
accidental poisoning.
Neutralize the poison by giving the victim plenty of milk to drink, an egg white or water.
If the poison is on the skin:
Remove any clothing from the affected part.
Wash the affected area thoroughly with a lot of water.
Do not apply any ointment.
Make sure the person is breathing. If not, start rescue breathing and CPR.

Note: Take the poison container or any pills, pill bottle or pill blister pack with you to the hospital.

Shock

Shock
is a condition in which the body system fails to take enough blood to
the vital organs. If untreated, it can lead to permanent organ damage or
death. The vital organs include the heart, the lungs, the brain, the
kidneys and the liver.

Causes

Shock
may result from bad news, heatstroke, severe illness, blood loss,
dehydration, poisoning, severe burns, an accident or other causes.

Signs and symptoms

Various signs and symptoms appear in a person experiencing shock. They include the following:

The skin becomes cool and moist. The skin, lips and fingernails may appear pale or grey.
The pulse rate is weak and rapid. Breathing may be slow and shallow.
The limbs may tremble and get weak.
The eyes lack lustre and may seem to stare. Sometimes the pupils are dilated.
As
the shock develops, the victim may experience nausea and even vomiting.
Eventually he or she may become restless, nervous, aggressive and
finally conscious or unconscious. If conscious, the person may feel
faint or be very weak or confused.

Procedure

Control any cause of shock such as bleeding, etc.
Lay the person down with his or her feet higher than his or her head (shock position).
Loosen tight clothing, laces, belts and shoes.
Turn the person on his or her side to prevent choking if the person vomits or bleeds from the mouth.
Keep the person warm and comfortable if he/she feels cold. Cover the victim with a blanket or any heavy clothing.
Seek treatment for injuries such as bleeding or broken bones.
Administer CPR if the person does not appear to breath well, cough or even move.
Seek medical help immediately.

The shock position

Electric shock

An
electric shock occurs when a person comes into direct contact with
electricity. Exposure to electricity may result in injury or even death.
Injuries may be burns, or physical injuries that result from being
thrown by the electric current.

Procedure

Switch off the main switch immediately if possible.
If
not possible to put off the switch, detach the casualty from the source
of electricity using a non-conducting object such as a dry wooden
stick, cardboard, plastic or rope.
Loosen any tight clothing, necklaces, bangles, etc.
If the person is unconscious, apply mouth-to-mouth respiration (CPR) immediately.
Treat
for shock, burns, bruises or other injuries the victim may have
sustained. Lay the victim down, and if possible, position the head
slightly lower than the trunk, with the legs elevated (shock position).
Take the person to the hospital immediately.

Caution

Do not touch the person with your bare hands if he or she is still in contact with the electric current.
Do not get near high-voltage electricity until power is turned off. Instead, call for help immediately.
Do not move a person with an electrical injury unless the person is in immediate danger.

Bruises

A
bruise is an injury beneath the skin. Bruises can be identified by
pain, swelling or a mark under the skin. A bruise forms when a blow
(hard hit) breaks the blood vessels near the skin’s surface. This allows
a small amount of blood to leak into the tissues under the skin. The
trapped blood appears as a blue-black mark.

Procedure

Wash the bruised part of the body.
Apply
a cold compress, such as a cloth dipped in cold water or ice wrapped in
a cloth, to the injury. This helps reduce pain, swelling, and speeds up
recovery.
If the bruise is on a limb such as arm or leg and it
covers a large area, keep the limb elevated as much as possible for the
past 24 hours.
After 48 hours, apply a cloth dipped in tepid
water to the bruise for about 10 minutes, three times a day. This will
help increase blood flow to the affected area and thus speed up healing.

Bruises under the skin

Vomiting

Vomiting is an involuntary ejection of the contents of the stomach through the mouth.

Possible causes of vomiting

Allergic reactions
Diseases e.g. malaria
Physiological condition e.g. pregnancy
Food poisoning
Unpleasant smell or taste
Drinking contaminated water.
Inhaling poisonous fumes
Over-eating.

Procedure

Give the victim an oral rehydration drink or oral rehydration salt solution. You may also provide a lot of any clear fluids.
Allow the person to have a complete rest.
Take the victim to hospital if:
Vomiting continues persistently.
The victim vomits blood.
The victim experiences high fever.
The victim is very dehydrated. This will be observed when the mouth and skin become very dry.

A victim vomiting

Fainting

Fainting
is a sudden loss of consciousness caused by a temporary fall in the
supply of blood and oxygen to the brain. Sometimes it can be caused by
emotional shock or prolonged standing. The person feels weak, sweats and
then falls down.

Procedure

Loosen or remove any tight clothing from the victim.
Make the victim lie down on his or her back.
Raise
the legs of the victim (shock position) above the level of his or her
head. This will increase the flow of blood to the brain.
Make sure the victim is exposed to plentiful supply of fresh air.
If there is no improvement in a few minutes, rush the victim to the hospital

Caution: Do not try to warm the victim

Muscle cramps

A
muscle cramp is an involuntarily and forcibly contracted muscle that
does not relax. A muscle that contracts involuntarily is called a
‘’spasm.’’ If the spasm is forceful, it becomes a cramp. Therefore,
muscle cramps occur because of uncontrolled muscle spasms.

Signs and symptoms

A sharp, sudden and painful spasm, or tightening of a muscle (especially common in the legs).
Muscle hardness
Twitching of the muscle
Persistent cramping pains in the lower abdominal muscles.

Causes

Imbalance in certain minerals, body fluids, hormones, and chemicals that allow stretching and contracting of our muscles.
Malfunctioning in the nervous system.
Excessive
physical activity and hormonal imbalances cause us to sweat. This
brings about the loss of many essential minerals, such as potassium and
calcium, which our body muscles need.

Procedure

Lay the victim down
Gently massage and stretch out the cramped muscle(s).
Apply some anti-cramp ointment to the affected area
If the problem persists, seek medical help immediately.

Stretching and massaging the muscles

Hiccups

Hiccups
are caused by sudden involuntary contraction of the diaphragm muscles,
giving a characteristic ‘’hic’’ sound. Numerous cures for hiccups exist.
These cures are thought to work because they increase the level of
carbon dioxide in the blood, which usually stops hiccups. (See procedure
1-3 below). If the vagus nerve that runs from the brain to the stomach
is stimulated, hiccups can also be alleviated.

Procedure

Give the affected person a polythene bag and encourage him/her to re-breath her own expelled air.
Ask the person to drink a glass of cold water quickly.
Tell the victim to hold his/her breath for as long as possible.
Ask the victim to pull on his/her tongue.
The victim may swallow finely crushed ice.
Children can be given a teaspoonful of a weak solution of sodium bicarbonate or lemon juice.
Place
one teaspoonful of dry sugar or honey on the back of the victim’s
tongue. (You can repeat this process 3 times at 2-minute intervals)

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

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

	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

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.

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