INTRODUCTION TO LABORATORY PRACTICE
INTRODUCTION
As explained in previous topic of introduction to physics that physicists use the scientific methods to test the hypothesis and develop scientific laws. These scientific method are carried out in a special room called laboratory.
Under this topic, we are going to learn about this special room, the equipment and apparatus must be there in the room and how to use them when conducting an experiment in the laboratory, again we shall discuss the safety guidelines of the laboratory.
Finally we shall discuss the basic principles of science investigation used in solving problems of the society. Your welcome and let get started;
What is laboratory?
Laboratory is the special room that have been designed and equipped for carrying out scientific experiments. Various instruments and chemicals used in performing experiments are usually stored in the laboratory.
Feature of Laboratory
There are some conditions needed in order to establish a laboratory. The following are features (conditions) needed for the establishment of a good laboratory;
i. There should be a water supply system
ii. There should be a drainage system
iii.There should be a electricity supply
iv. It should be well illuminated
v. It should be well ventilated
vi.There should be the door open out ward
vii.There should be a gas supply or any other source of heat
Types of laboratory
- Clinical and medical laboratory
- Physics laboratory
- Chemistry laboratory
- Biology laboratory
What is Physics laboratory?
Physics laboratory is a working room for physicists. The physics equipment and apparatus are kept in this room and different physics experiment are carried out.
Laboratory Apparatus
Laboratory apparatus is the special tools and instruments designed to carry out the experiments in the laboratory.
The following table shows the physics apparatus and their uses.
ITEMS | USES | |||||
Measuring cylinder | For measuring volume of liquids |  | ||||
Thermometer | For measuring temperature of substances |  | ||||
Stop watch | To measure time |  | ||||
Micrometer screw gauge | For measuring diameter of a wire |  | ||||
Vernier caliper | For measuring depth, length, internal and external diameters of objects |  | ||||
A ruler | For measuring length |  | ||||
For measuring relative density |  | |||||
Microscope | For magnifying very small objects |  | ||||
Beaker | Used as container for chemicals and other liquids. Also can be used to estimate the volume of liquids |  | ||||
Calorimeter | Used in experiment aimed at determining the quantity of matter |  | ||||
|
|  | ||||
| For demonstrating attraction and repulsion |  | ||||
| For demonstrating thermal expansion |  | ||||
| To show forces that can be exerted during thermal expansion and contraction |  | ||||
| For providing a platform for heating for stability |  | ||||
| As source of heat |  | ||||
| For holding/gripping materials |  | ||||
| Measuring mass |  | ||||
| For holding liquids during experiment |  | ||||
| For transferring specific but small volume of liquids |  | ||||
| For measuring volume of liquid |  | ||||
| For measuring mass in |  |
Laboratory Rules
Laboratory rule is the set of guidelines governing physicist to conduct experiment and are to be followed in the laboratory in order to reduce risks of accidents.
In the laboratory individuals are advised to follow to specific laboratory rules to ensure their safety, and other people working in the laboratory and the safety of the apparatus and chemicals stored in the laboratory.
Laboratory Rules
The followings are some of the physics laboratory rules.
i. Do not enter laboratory without permission
ii. Do not do an experiment without permission
iii. Do not start experiment without procedure information
iv. Follow instruction careful to avoid damage of apparatus
v. Follow instruction careful to avoid wrong result
vi. Handle apparatus with care to avoid damage
vii. Avoid handling apparatus and chemical until you asked by your teacher
viii. Avoid running, screaming or playing in the laboratory
ix. Avoid tasting, eating or drinking anything in the laboratory
x. Keep the window open for any fumes to flow out
THE SAFETY MEASURES IN THE PHYSICS LABORATORY
Laboratory Safety
Laboratory safety is the situation in laboratory whereby physicist protected from danger, risk or injury. These safety measures include;
1. All experiments which produce poisonous fumes must be conducted in the fume chamber.
2. The laboratory floors should not be polished to avoid slipperiness.
3. The laboratory should have large windows and doors which should be opened outwards.
4. Ensure that the fire extinguisher is fixed at an appropriate place, ready to be accessed in case of fire outbreak.
5. In a multi store building, a Physics laboratory should be in the lowest floor.
Now, you can take the assessment for this sub- topic
FIRST AID AND FIRST AID KIT
What is First Aid?
First Aid is an immediate care given to accident victim(s) or an injured person before he/she is taken to a nearby hospital for further medical treatment.
While working in the laboratory scientist try to avoid accidents but sometimes accidents may occur and may be caused by many factors like disobeying of the laboratory rules and careless of a person. When accident occur a person get injured and is said to be a victim or an injured person.
A victim should be given first treatment early before his or her condition get worse. This aid should be of hurry means should be provided immediate after an accident and is referred to as first aid.
Importance of First Aid
i. It helps to preserve life
ii. It prevents the victim’s condition from becoming worse
iii.It promotes recovery by bringing hope and encouragement to the victim
iv. It helps to reduce pain and suffering
v. It prevents infection
What is First Aid Kit?
First Aid Kit is the small box containing necessary items (instruments and chemicals) needed to provide first aid.
Usual labeled as “FIRST AID” and stored in a safe and easily accessible place in a laboratory. Take a look for the box below;
Inside the first aid kit there are items that are used to provide the service to an injured person. The following table shows the first aid items, their uses and how they look like.
ITEMS | USES | How it looks like |
1. Pair of scissors | To cut adhesive tapes, bandages and gauze |  |
2. Rolls of adhesive tape | To hold firmly into wounds bandages, gauze and cotton wool |  |
3. Cotton wool and Bandages | To clean and cover wounds |  |
4. Sterilized new razor blades | Used when treating new or old wounds |  |
5. Sterilized gauze | To clean and cover wounds |  |
6. Safety pin | To tighten clip bandages |  |
7. One jar of petroleum jelly | To apply on burns |  |
8. Iodine tincture | To clean fresh cuts and bruises |  |
9. Soap | To wash hands and wounds |  |
10. Antibiotic solution | To clean wounds |  |
Causes of Laboratory Accident
Some of the common causes of accidents in a science laboratory include the following:
1. Ignoring laboratory rules
2. Improper arrangement of laboratory instruments and chemicals
3. Playing, fighting or quarreling in the laboratory
4. Performing unauthorized experiment or deviating from instruction of experiment.
5. Gas leakages from faulty gas taps
6. Incorrect use and handling of apparatus
FIRST AID PROCEDURES
These are steps to be followed to help the victim when accident occur. When accident occur to the victim there are some procedures that must be followed to provide the first aid.
The followings are some of the accidents that might occur in the laboratory and their specific procedures;
(i) Electric shock
(ii) Cuts (or wounds)
(iii) Fainting
(iv) Fire
Electric shock
An electric shock occurs when a person comes into contact with an electrical energy source.
Electrical energy flows through a portion of the body causing a shock.
The following steps (procedures) are to be followed when dealing with a victim of electric shock;
(i) Do not touch the victim who still in contact with electric current.
(ii) Turn off the source of electricity, if possible.
(iii) If not, move the source away from you and the person, using a dry, non-conducting object made of cardboard, plastic or wood.
(iv) If the victim is unconscious, check the breathing and pulse rate.
(v) Provide First Aid for shock, burns or other injuries obtained by the victim.
(vi) Seek medical assistance.
Cuts or Wounds
A cut is a break or opening in the skin. It may be near the surface of the skin, or deeper.
A wound is a puncture caused by a pointed object such as a nail, knife, or sharp tooth.
The following steps (procedures) are to be followed when dealing with a victim of cuts or wounds
(i) Wash your hands using soap and cleaning water.
(ii) Put on your gloves.
(iii) Wash your wounds using salty water and clean cloth.
(iv) Cover the wounds or cut with an adhesive bandage or plaster.
Fainting
Fainting is the situation where by victim is weak and unable to stand. It caused by too much heat and congestion.
The following steps (procedures) are to be followed when dealing with a victim of fainting;
(i) Take the person to a cool place or under a shade.
(ii) Let the victim lie on his back with his legs raised higher than the head.
(iii) Loosen his clothes and ensure sufficient supply of air.
(iv) Dip a clean handkerchief in clean water and press on his forehead.
(v) Give him/her clean water to drink when he regains consciousness
(vi) If necessary, take the victim to the nearest hospital.
Fire
Fire is a process in which substances combine chemically with oxygen from the air and typically give out bright light, heat, and smoke; combustion or burning.
Fire Triangle
The fire triangle is a simple way of understanding the elements of fire.It has the components needed to start a fire.
This include;
i. Fuel
ii. Oxygen
iii. heat
Class of Fire
Fire are classified according to materials burnt.
There are six classes of fire: Class A, Class B, Class C, Class D, Class E and Class F.
Class A fires – combustible materials: caused by flammable solids, such as wood, paper, and fabric.
Class B fires – flammable liquids: such as petrol, turpentine or paint.
Class C fires – flammable gases: like hydrogen, butane or methane.
Class D fires – combustible metals: chemicals such as magnesium, aluminum or potassium.
Class E fires – electrical equipment: once the electrical item is removed, the fire changes class.
Class F fires – cooking oils: typically a chip-pan fire
The following table shows each class of fire and its fire extinguisher.
Fire class | Burning materials | Suitable Fire Extinguisher |
A | Combustible materials; caused by flammable solids, such as wood, paper, and fabric. | Use any type of Fire extinguisher except carbon dioxide. However, water is suitable. |
B | Flammable liquids: such as petrol, turpentine or paint. | -Use fire blanket or sand extinguisher if fire is a small - Use dry powder, foam or carbon dioxide extinguisher if fire is large |
C | Flammable gases: like hydrogen, butane or methane. | Use dry powder, foam or carbon dioxide extinguisher |
D | Combustible metals: chemicals such as magnesium, aluminum or potassium. | Use dry powder, foam or foam extinguisher |
E | Electrical equipment: once the electrical item is removed, the fire changes class. | Use carbon dioxide extinguisher Nb: first switch off power from the mains switch |
F | Cooking oils: typically a chip-pan fire. | Use wet chemical extinguishers |
Why carbon dioxide not suitable for fire class A?
Answer: When molecules of carbon dioxide reach fire gain heat and result lowered its density then escape away for fire and the fire continue.
Why water not suitable for fire class A?
Answer: Water is denser than flammable liquid so flammable liquids will float over water results the fire continues.
After discussing the fire now let take a look on the causes of fire in the laboratory as one of the accident.
Causes of Laboratory Fire
i. Electrical faults
ii. Smoking materials
iii. Carelessness
iv. Ignorance and negligence
Basic Principles of Fire Prevention
i. No light of open fires near buildings
ii. No smoking in prohibited areas
iii. No interference with electrical installations
iv. all electrical appliances must off after use
v. all sources of heat should not have kept near the bench edge where they can easily be knocked down
vi. all flammable substances should be locked up in drawers or cabinets
WARNING SIGNS
A warning sign is a type of sign which indicates a potential hazard, obstacle or condition requiring special attention. These sign are used to warn a person about a possible dangers in a given area and when using the item.
In the laboratory these symbols are used to warn a person and possible laboratory danger while he or she is in the laboratory and when using various chemicals. They include the followings;
i. Toxic
ii. Irritant/harmful
iii. Flammable
iv. Oxidizing agent
v. Corrosive
vi. Radio active
vii. Danger of electric shock
viii. Fragile
ix. Explosive
x. Careful
xi. Keep away from water
Toxic
Toxic symbol means that a substance is dangerous and can cause death within a short time. Toxic substances containing poisonous ingredients, Example, of toxic substance is jik, mercury etc.
Toxic Substance Enter the Body Through;
i. Ingestion (by eating and drink)
ii. Inhalation (by breathing)
iii. By injection (by syringe, bite or insect)
iv. Contact (by touching)
Irritant/Harmful
Harmful symbol means that a substance is dangerous and can affect our health for long time. Example, of harmful substance is alcohol, paint, insecticide, tobacco, ammonia etc, mercury etc.
 |
| Harmful |
Flammable
Flammable symbol means that the substance can catch fire easily. For Example, , gas oil, kerosene, petrol, butane, methane, spirit, nail polish remover, turpentine etc.
Oxidizing Agent
Oxidizing agent symbol means that the substance can speed up the rate of burning. For Example, , oxygen gas, chlorine gas, fluorine gas and hydrogen peroxide.
Corrosive
Corrosive symbol means that the substance causes gradual change if contact with various materials. For Example are concentrated sulphuric acid, concentrated hydrochloric acid, concentrated nitric acid, concentrated sodium hydroxide, concentrated ammonia etc.
Radio Active
Radioactive symbol means that the substance emits harmful radiations that penetrate human body and cause damage. For Example, , uranium, plutonium etc.
Danger of Electric Shock
Danger of electric shock symbol means that the substance has high voltage which should not touch.
Fragile
Fragile symbol means that the substance should handle with care to prevents them from breaking. For Example, glass etc.
Explosive
Explosive symbol means that the substance can erupt/explode easily. Always sore in a special container.
Nb:
Never store explosive material in glass container because when explode pieces of glass would fly all over and injure people.
Careful
Careful symbol that is the caution advice you to be carefully.
Keep Away from Water
Keep away from water symbol that is the caution advice you to keep item away from the water. For Example, computer, mobile phones, radio etc.
Scientific Investigation
Scientific investigation is a quest to find the answer to a question using the scientific method.
The scientific method is a systematic process that involves using measurable observations to formulate, test or modify a hypothesis.
The hypothesis is a proposed explanation for some observed phenomenon, based on experience or research.
Steps of scientific investigation
There are 8 common steps to follow when doing a scientific investigation.
1. Identification of a problem - This is the first step where a problem is recognized or observed. For example, a scientist may observe that every day at noon his/her bicycle tire bursts.
2. Asking questions – At this stage a scientist asks self-questions about the observed problems. For example, does the hot weather at noon cause the observed tire bursts?
3. Hypothesis formulation – This is the stage where a scientist guesses the possible causes of the observed problem. The scientist tries to guess intelligent answers about the questions asked in the second step for example, bursting of the tire is mainly caused by the hot temperature at noon. The hypothesis can be true or false.
4. Experimentation – At this stage, the hypothesis is being tested scientifically. An experiment is a test conducted in a controlled condition or environment such as in a laboratory. The aim of the experiment is to obtain scientific answers or data about the observed problem. Data is a set of facts, values or details which can be translated to give a meaning.
5. Collection of data and analysis – During experimentation, results or data obtained are collected and recorded in a good and systematic manner. One good way of recording data is by using tables (tabular form).
6. Data interpretation – At this stage, the data recorded are related to one another to obtain the relationship between them. For example, it may be found that as the temperature of the surroundings increases the size (volume) of the tire becomes large.
7. Presentation of data – This is when the data or information obtained is put in a form that can be well understood. In this stage, mathematical formula, graphs and diagrams can be used to explain the results.
8. Conclusion – This is when a scientist comes out with a statement or summary to agree or disagree with the hypothesis according to the results obtained from the experiment. The scientist provides the possible solution to the problem observed on the first step. For example, the bursting of a tire at noon is caused by enormous expansion of air inside the tire brought by rise in temperature.
The following chart show the summary of the scientic procedures
Application of Scientific Procedure
i. To gain new knowledge.
ii. To find information on subject/problem.
iii. To find answer to problems and to test hypothesis.
Significance of the Scientific Procedure
i. It helps us to solve scientific problems
ii. It helps us to gain new knowledge
iii. It helps us to conduct project work
iv. It helps us to carry out field study
v. It helps us to solve problems or answer scientific questions.
______________________________________
Post a Comment