CHEMISTRY FORM ONE NOTES

Chapter One: Introduction to Chemistry

Introduction

Chemistry is fundamental to our world. It has a variety of roles and impacts on several aspects of life, including food, medicine, manufactured products, advancement of technology, and the environment. In this chapter, you will learn about the concept of chemistry, the relationships of chemistry with other related disciplines, and applications of chemistry in the development of a modern society. The competencies developed will enable you to apply chemistry skills, theories and principles to solve daily life challenges.

Think

The contributions of chemistry in various aspects of life.

Concept of Chemistry

Task 1.1

1. Use reliable online sources to search for images or pictures of various materials produced by chemical processes and identify those commonly found in your environment.
2. Examine the properties such as colour, size and physical state of the materials.
3. Watch animated videos illustrating the composition of chalk, soft drinks or water, and how water undergo changes from liquid to solid state.
4. Explain the meaning of chemistry based on the task performed.

Chemistry is a branch of science that deals with the composition, structure and properties of matter, and the changes that matter undergoes. Matter is anything that has mass and occupies space. It includes the materials or substances of nature which make up our environment.

Chemistry is divided into different areas such as:

• Analytical chemistry - deals with the studies of instruments and methods used to separate, identify, and quantify chemical species in matter.
• Inorganic chemistry - deals with properties and behaviour of inorganic compounds.
• Organic chemistry - deals with properties and behaviour of organic compounds.
• Physical chemistry - is concerned with the relations between the physical properties of substances and their chemical composition and transformations.
• Chemical engineering - deals with operations, designs and methods of improving production.
• Biochemistry - deals with the study of chemical processes that occur in living things.

The people who study chemistry are called chemists. Since chemistry is a science that involves experiments and practical work, chemists must acquire scientific skills to successfully obtain facts and verify them. These skills include:

1. Making thorough observations;
2. Recording accurately what has been observed;
3. Organising the observed and recorded information;
4. Repeating tests to ensure observations are accurate;
5. Drawing conclusion from observations; and
6. Predicting possible outcomes of similar experiments.

Therefore, chemistry students should apply these skills to be able to think logically and critically.

Relationships of Chemistry with Other Related Disciplines

Task 1.2

Conduct a library and internet search on the relationships between chemistry and other related disciplines and prepare a report.

Chemistry is not an isolated discipline, because it is related to other disciplines such as, biology, physics, agriculture, geology, environmental sciences and mathematics. Studying the relationships of chemistry with other related disciplines is important as it helps to understand the world around us and give insight to physical, chemical and biological processes. It also provides useful integrated skills and acts as a foundation for understanding scientific skills through researching different phenomena.

The relationships of chemistry with other related disciplines help to understand different professions resulting from learning chemistry. A person studying chemistry with other disciplines may become a medical doctor, pharmacist, nurse, chemical analyst, laboratory technician, laboratory scientist, researcher, chemical engineer, teacher and environmentalist. This means chemists find employment opportunities in hospitals, pharmaceutical industries, research centres, testing laboratories, schools, energy sectors, chemical industries, food processing industries, biotechnology firms and other manufacturing industries.

The following are some disciplines which are related to chemistry:

Biology

Chemistry and biology are closely related disciplines. These disciplines converge in biochemistry and biotechnology fields. Biochemistry explores the chemical processes that occur within living organisms for understanding biological systems. On the other hand, biotechnology is the use of living organisms to produce economically useful products. These products are produced by integrating the knowledge and skills from chemistry, biology and chemical engineering. Therefore, the relationships of these disciplines bring development that resolves daily life challenges related to agriculture, medicine, nutrition and environmental science.

Physics

Chemistry has a strong interrelation with physics and forms the foundation for understanding the physical world and the behaviours of matter. Chemistry and physics converge in physical chemistry. This field drives innovations and technological advancements in various areas such as medical instruments, materials science and products from manufacturing industries.

Agriculture

Chemistry is closely related to agriculture through agro-chemistry. Agro-chemistry examines the chemical processes related to plants, animals and soil health, crop protection and fertilisers. This field helps in ensuring food availability and security as well as good agricultural practices which enhance the quality of agricultural products.

Geology

Chemistry and geology disciplines integrate through geochemistry field. This field applies chemistry theories and principles in exploring the chemical composition and processes of Earth and other planets. Geochemists use their expertise in investigating the abundance and distribution of chemical elements in rocks and minerals which is the foundation of mining industry.

Environmental Sciences

Environmental chemistry and atmospheric chemistry are among the fields which provide relationships between chemistry and environmental science. These fields apply chemistry theories and principles to study the interactions of chemicals in the environment, including pollution and their impacts to the natural world.

Mathematics

Mathematics is applied in almost all areas of chemistry including physical chemistry, analytical chemistry, inorganic chemistry, organic chemistry and biochemistry. It serves as a powerful tool for various aspects of chemistry such as analysis of chemical processes that involve interactions and changes of matter, and the interpretation of experimental data through statistical analysis which may be used to draw conclusions in chemistry experiments. It is also applied in measuring mass, volume, temperature and concentration of chemical substances, calculating percentage and ratios that express concentrations, composition and yields of chemical reactions as well as computational chemistry which uses mathematics to simulate chemical processes, predict structures and calculate properties of chemical systems.

The relationships of these disciplines make meaningful contributions for advancement of the chemistry related fields such as medicines, pharmacy, agriculture and environmental chemistry. Therefore, mathematics allows individuals to conduct precise experiments, make predictions and develop deep understanding on the principles governing the behaviours of matter.

Applications of Chemistry in the Development of a Modern Society

Project

Visit a nearby manufacturing industry, health facility, mining site or agricultural farm to identify materials produced through chemical processes, study the practical applications of chemistry in the development of modern society, and prepare a report.

Chemistry plays a significant role in the development of a modern society. It is applied in a wide range of industrial processes and daily life activities. It has influenced most aspects of life including healthcare, energy production and environmental sustainability. The quality of life for most people worldwide has improved due to practical applications of chemistry. Many of the products that are obtained by the applications of chemistry are useful for development of modern societies. These products are processed in different areas such as agriculture, medicine, nutrition and cooking, and manufacturing industries.

Agriculture

Agriculture is the practice of growing crops and keeping animals. Farmers use many products made through chemical processes to obtain better agricultural yields. These products include fertilisers, pesticides, animal vaccines and processed animal feeds. Fertilisers are used to improve the quality and quantity of crops. Pesticides are used to destroy or control pests harmful to crops, animals, or their products. Animal vaccines are used to protect animals against various infectious diseases.

Medicines

The field of medicine ensures our well-being through the prevention and treatment of diseases. Chemically produced substances in the forms of vaccines and medicines are used in this field.

Nutrition and Cooking

Chemistry has an impact on the tastes, textures and nutritional value of food. Understanding chemistry helps in identification of different food components including carbohydrates, proteins, fats and oils, vitamins and minerals. Chemical reactions involved in cooking help to have foods that are healthy and palatable.

Manufacturing Industries

Manufacturing industries such as textile, chemical, paper, food and beverage, transport industries, communication, plastic manufacturing, and construction materials industries rely heavily on chemical processes. Most of the machine parts are made of metals, plastics and rubber. These materials are produced through chemical processes.

Food and Beverage Industries

The food and beverage industries have benefited greatly from chemical processes and products. Among these processes is the preservation of foods, especially canned or bottled. Examples of chemicals commonly used as food preservatives are common salt, sodium nitrite, citric acid, sodium benzoate and alcohol.

Transport

Fuels and lubricants used in motor vehicles, aircraft, motorcycles, ships and other means of transportation are produced by chemical processes. Their parts such as engines, batteries and tyres are made through chemical processes.

Communication and Technology

Chemistry plays a significant role in communication and technology, from the development of batteries and electronic devices to the transmission of data through various networks. Applications of chemistry principles give impact on innovation and advancement of technology.

Home Care Products and Cosmetics

Home care products are chemically made materials used to clean the home and its surroundings, making them more comfortable to live in while ensuring effective hygiene and personal care. These products include soaps, detergents, disinfectants, air fresheners and polish. Cosmetics are also produced chemically. They are used to improve one's physical appearance or odour.

Exercise 1.1

1. Using examples of chemical substances, explain how chemistry is commonly applied in your community.
2. How do the chemistry skills contribute to the understanding of environmental science field?
3. How does chemistry influence the development of a modern society?

Chapter Summary

1. Chemistry is a branch of science that deals with the composition, structure and properties of matter, and the changes that matter undergoes.
2. The people who study chemistry are called chemists.
3. Chemists use various theories and principles from chemistry and other related disciplines including biology, physics, agriculture, geology, environmental science and mathematics to understand the world around us and give insight to physical, chemical and biological processes.
4. The skills acquired in chemistry and other related disciplines can enable a person to develop different professions such as medical doctor, pharmacist, chemical analyst, chemical engineer, teacher, laboratory technician, laboratory scientist, environmentalist, nurse, biotechnologist and researcher.
5. A lot of materials are made through the application of the knowledge, skills and principles of chemistry. The materials include soaps and detergents, foods and drinks, medicines, fuels and cosmetics.
6. Chemistry is important because it is applied in many areas such as agriculture, medicines, food and beverage industries, home care and cosmetics industries, research, transport, and communications and technology. Therefore, the applications of chemistry in these areas assist in the development of modern society.

Revision Exercise 1

Choose the correct answer in items 1-5.

1. If a Form One Student aspires to be a professional farmer, which among the following subjects a student should be advised to focus on in order to develop the necessary competencies?
   (a) Geography, physics and chemistry
   (b) Biology, physics and mathematics
   (c) Agriculture, chemistry and biology
   (d) Chemistry, physics and biology
2. Imagine that, you are playing a chemistry-related trivia game with your friends. If you are to choose one term which does not relate to any recognised branches of chemistry among the following, which term could you choose?
   (a) Organic chemistry
   (b) Arithmetic chemistry
   (c) Inorganic chemistry
   (d) Physical chemistry
3. What are some of the main purposes of vaccines as chemical substances?
   (a) Cure animals and human beings from diseases.
   (b) Protect animals and human beings from diseases.
   (c) Introduce vitamins and proteins in animals.
   (d) Make animals grow faster than normal.
4. Which of the following terms refer to a person with specialised knowledge and expertise in the field of chemistry?
   (a) Alchemist
   (b) Chemistry
   (c) Chemist
   (d) Pseudo-chemist
5. A person at home can apply chemistry in:
   (a) playing games.
   (b) watching television.
   (c) cooking food in a kitchen.
   (d) dusting the floor in a house.
6. Explain how chemistry principles are used in making water clean and safe.
7. What is the role of chemistry in overcoming health problems?
8. Use relevant examples to support the statement, "agriculture and chemical industry can work together rather than separate".
9. In what ways have modern societies benefited from chemistry through communication and advancement of technology?
10. How does the application of chemistry contribute to a clean environment?

Chapter Two: Laboratory Techniques and Safety

Introduction

Most of the chemistry experiments in schools take place in a special room called laboratory. In this chapter, you will learn about laboratory safety measures, First Aid and basic chemistry laboratory apparatus. The competencies developed will enable you to protect yourself in the laboratory and apply the best ways of handling apparatus and chemicals as well as home delicate appliances. Moreover, you will develop knowledge and skills in providing First Aid to sick or persons injured in accidents that may occur in the laboratory, in public places and at home.

Think

The appropriate use of the laboratory enhances safety to users and equipment.

Laboratory Safety Measures

Task 2.1

Watch a video which illustrates the laboratory safety measures. Note all features illustrated in the video and compare them with the features of your laboratory.

Safety in the laboratory is of great importance to its users. This is because the experiments performed in a chemistry laboratory often involve the use of delicate or complicated equipment and harmful chemicals. In this regard, activities carried out in the laboratory always require measures to prevent risks. It is important to minimize these risks to protect people and the environment.

The following are some of the safety measures to be taken in the laboratory:

1. The laboratory should be equipped with working fire extinguishers fitted in accessible positions with clear instructions on how to use them in case of fire accidents.
2. Cupboards, storage cabinets and drawers should have locks.
3. Laboratory floors should not be polished to avoid slipperiness.
4. All apparatus should be regularly checked to ensure that they are safe for use.
5. All laboratory users should wear appropriate protective gears to minimise exposure to hazards.
6. Emergency exits should be present, easy to access and use. Doors should open outward.
7. There should be a manual or instructions on how to treat spills of different chemical substances present in the laboratory.
8. Gas cylinders should be labelled, well stored and supported.
9. Each laboratory should contain a First Aid Kit with all the necessary items.
10. Refrigerators and freezers used in the laboratory should be labelled "For chemical use only".

Handling Chemicals Safely

Working in the chemistry laboratory requires great care because many chemicals are poisonous and can cause death. The hazards of the chemicals in the school laboratory should be identified by checking the safety signs labelled on their containers. All chemicals which are not correctly labelled should be removed from the laboratory and destroyed using proper methods.

Safety Signs

Some safety signs have words and clear messages while many rely on visual symbols to warn for the potential hazards or to provide instructions for safe usage of the chemicals.

S/N	Sign	Meaning
1.	Corrosive	Corrodes surfaces as well as the human skin
2.	Toxic	Poisonous and can cause death
3.	Oxidant	Readily gives off oxygen or other oxidising materials. May intensify fire and cause explosions
4.	Flammable/inflammable	Catches fire easily
5.	Explosive	Blasts easily
6.	Caution	Hazardous, can cause damage to organs from a short-term exposure
7.	Health hazard	Hazardous, can cause serious long-term health effects such as cancer, breathing difficulties and damaging of organs

Activity 2.1

Aim: To demonstrate the effect of concentrated acids on different materials.

Requirements: Concentrated sulfuric acid, 3 white tiles, dropper, pieces of paper, cloth and pieces of metals

Caution: Sulfuric acid is highly corrosive. Handle it with care.

Procedure:

1. Place each item on a separate white tile.
2. Using a dropper, pour few drops of concentrated sulfuric acid onto each item on a white tile. Be very careful not to spill the acid on yourself, others or on the worktable.
3. Observe and record the results.

Question: What happened when few drops of concentrated sulfuric acid came into contact with each item?

Laboratory Rules

A laboratory rule is a statement that explains what to do or not to do in the laboratory. Experiments should be conducted in the laboratory by following proper procedures. It is important to follow laboratory rules in order to have successful practical activities in the laboratory and to avoid some hazards.

Task 2.3

Make a chart of at least ten important laboratory rules. You can use pictures, signs and artwork in your charts. The best chart will be pinned up on the laboratory noticeboard. Why should laboratory rules be obeyed by everyone?

Laboratory Rules Before Practical Activities

1. Do not enter in the laboratory without the permission or presence of the teacher or laboratory technician.
2. Dress appropriately for the laboratory activities. Wear a laboratory coat and safety goggles.
3. Keep the windows open for proper ventilation.
4. Identify and note locations of all exits.

Laboratory Rules During Practical Activities

1. Read the instructions carefully before you start any activity.
2. If you do not understand something, ask your teacher or the laboratory technician before proceeding.
3. Read the labels on chemical containers to be sure you have the right substance.
4. Do not eat, drink, smoke, play or run in the laboratory.
5. Do not taste or smell a chemical or anything unless you have been instructed on how to do it.
6. Use a fume chamber when carrying out experiments which produce harmful gases and vapours.
7. Perform the intended experiments only.
8. Do not spill liquids on the floor.
9. Report any breakages or accidents to the teacher or laboratory technician immediately.

Laboratory Rules After Practical Activities

1. Appropriately dispose-off any wastes.
2. Do not pour concentrated chemicals into the sinks.
3. Clean up the equipment and store them safely.
4. Turn off gas and water taps.
5. Clean the working surfaces, benches and sinks.
6. Wash your hands with soap and running water.

First Aid

First Aid is an immediate help given to a person who is sick or injured before a professional medical assistance is available. It is important to learn the basics of First Aid because accidents can occur in the laboratory.

The First Aid helps to:

1. reduce the likelihood of death.
2. shorten the recovery time.
3. prevent permanent disability.
4. reduce pain and suffering.
5. prevent the victim's condition from getting worse.

Causes of Accidents in the Laboratory

There are various causes of accidents in the laboratory. These include:

• Failure to follow the right procedure for the given experiments
• Spilled liquids left on the floor
• Chemical spills and exposure
• Wrong use of equipment
• Accidental swallowing of harmful chemicals
• Improper disposal of chemical wastes
• Poor ventilation in the laboratory
• Gas leakage from taps or cylinders
• Use of wrong reagents due to wrong labelling
• Electric shock
• Lack of adequate information on procedure and hazards
• Eating or drinking in the laboratory

First Aid Kit

A First Aid Kit is a box that contains items used to give help to a sick or injured person. Every laboratory should have a First Aid Kit.

Components of First Aid Kit and Their Uses

• First Aid guide - Contains guidelines on how to use the items in the First Aid Kit
• Plaster or adhesive bandage - Covering small cuts or wounds
• Sterile gauze - Covering wounds to protect them from dirt and germs
• Antiseptic - Cleaning wounds to kill germs
• Soap - Washing hands, wounds and equipment
• Razor blade or pair of scissors - Cutting dressing materials
• Safety pin - Securing bandages
• Bandage - Keeping dressings in place and immobilising injured limbs
• Cotton wool - Cleaning and drying wounds
• Clinical thermometer - Measuring the body temperature
• Disposable sterile gloves - Covering the hands to avoid infecting wounds
• Petroleum jelly - Smoothing dry, cracked and sore skin
• Liniment - Reducing muscle pains
• Torch - Source of light
• Whistle - Blown to call for help
• Painkiller - Relieving pain
• Gentian violet - Treating fungal infections and serious heat burns
• Iodine tincture - Preventing infections in fresh cuts, burns and scrapes

First Aid Procedures

Suffocation

Procedure:

1. Remove the cause if possible, or remove the victim from the cause of suffocation.
2. Ensure the victim's airways are open for air to reach the lungs.
3. Blow air into the victim's airways using a clean material.
4. Keep the victim warm using a light blanket.
5. Take the victim to a nearby health care facility.

Burns

Procedure:

1. Lay the victim down and protect the burnt area.
2. Gently pour cold water on the burn for about 10 minutes.
3. Check the breathing and pulse.
4. Gently remove any jewellery, shoes or burnt clothing.
5. Cover the burn with a sterile gauze and wrap it loosely.
6. Give the victim a pain reliever.
7. Take the victim to a nearby health care facility.

Caution:

• Do not use ice as it further damages the skin.
• Do not apply ointment or butter to the burn.
• Do not break any blisters as that can cause infections.

Electric Shock

Procedure:

1. Break the contact between the electrical source and the victim by switching off the power source.
2. If it is not possible to switch off the current, move the person using a dry non-conducting material.
3. If there is immediate danger, call for professional help immediately.
4. If the victim is unconscious, check the pulse rate and breathing.
5. Administer First Aid for burns, shock or other injuries.
6. Take the victim to a nearby health care facility.

Caution: Do not touch a person who is still in contact with electric current.

Basic Chemistry Laboratory Apparatus

Chemistry laboratory apparatus are special tools or equipment used in the laboratory. They serve various purposes such as measuring, testing, heating, filtering, grinding, holding, storing, scooping and safety.

Apparatus for Measuring

• Pipette - Used to measure specific volume of liquids
• Measuring cylinder - Used to measure volume of liquids
• Beaker - Used for measuring, mixing and stirring solutions
• Burette - Used to accurately measure and dispense known volume of liquids
• Thermometer - Used to measure temperature
• Electronic analytical balance - Used to measure the mass of substances
• Spring balance - Used to measure the weight of an object
• Stopwatch - Used to accurately measure time

Apparatus for Testing

• Test tube - Used for holding chemicals or heating substances
• Dropper - Used to add liquids drop by drop
• Flasks - Used for measuring and holding liquids
• Watch glass - Used to hold substances being weighed or observed
• Gas jar - Used for collecting and testing properties of gases
• Thistle funnel - Used to add small volumes of liquid reagents

Apparatus for Heating

• Burners and lamps - Used as a source of heat
• Boiling tube - Used to heat substances that need to be heated strongly
• Tripod stand - Support platform with three legs
• Wire gauze - Helps to spread out the flame and heat substances evenly
• Crucible - Container for heating substances to very high temperatures
• Evaporating dish - Used to heat and evaporate liquids and solutions
• Deflagrating spoon - Used to heat small amount of substances inside a gas jar

Apparatus for Safety

• Safety glasses or goggles - Protect the eyes from chemical spills and harmful vapour
• Laboratory coats - Protect clothing and skin from chemical spills
• Gloves - Protect hands from exposure to hazardous chemicals
• Face masks - Protect against airborne particles, gases and fumes

Activity 2.2

Aim: To measure the volume of a liquid using different apparatus.

Requirements: Pipettes, burettes, measuring cylinders, beakers and coloured water

Question: What is the volume of the coloured water in each of the measuring cylinders?

Chapter Summary

1. A chemistry laboratory is a special room where chemistry experiments are carried out.
2. Safety signs have symbols or words that warn for the potential hazards or provide instructions for safe usage of the substance.
3. First Aid is the help given to a sick or injured person before a professional medical help is available.
4. A First Aid Kit is a box that contains items used to give First Aid to a sick or injured person.
5. Laboratory apparatus is special tools and equipment used in a laboratory.

Revision Exercise 2

Choose the correct answer in items 1-8.

1. In rendering First Aid to an electric shocked victim, you must primarily think of:
   (a) checking whether the victim is breathing.
   (b) putting the victim in a recovery position.
   (c) administering First Aid for burns or injuries
   (d) breaking the contact with an electric source.
2. Some experiments require powdery chemicals. Which apparatus will you use to make them available out of the given granules?
   (a) Pestle and filter funnel
   (b) Round-bottomed flask and trough
   (c) Mortar and pestle
   (d) Bunsen burner and filter paper
3. In a discussion of the argument "access to safety equipment should never be blocked by any object." Which among the reasons can justify the statement?
   (a) It is just a simple law.
   (b) There must be spaces for people to move around in the laboratory.
   (c) The equipment is used every day.
   (d) It is important to reach safety equipment quickly in case of an accident
4. A Form One Student saw a flammable sign on a box. This suggest that the box is most likely to contain:
   (a) firewood.
   (b) papers.
   (c) radioactive materials.
   (d) spirit used in lamps.
5. Your chemistry teacher denied a student to enter the laboratory because of a floppy clothing. This is because the cloth may:
   (a) be blown by wind.
   (b) affect the measurements.
   (c) catch fire or cause one to fall.
   (d) cause poor ventilation in the body.
6. Imagine you are a class monitor/monitress and your chemistry teacher asked you to remind your fellow students on the laboratory rules before the practical session. Which rule will you insist to be adhered before a practical session?
   (a) Do not use dirty, cracked or broken apparatus.
   (b) Do not taste or smell chemicals.
   (c) Report any accident however small it may be.
   (d) Do not enter in the laboratory without permission.
7. Fainting is different from shock because fainting is a sudden loss of:
   (a) weight of the body.
   (b) consciousness.
   (c) confidence in mind.
   (d) water in the body.
8. The chemistry teacher gave students a list of laboratory apparatus and asked them to drop those that do not relate with chemistry. Which list could be dropped?
   (a) crucible and lid, evaporating dish and filter funnel.
   (b) wire gauze, test tube rack and deflagrating spoon.
   (c) burette, pipette and conical flask.
   (d) microscope, drawing board and prism.
9. Match the following apparatus with their uses.
10. A student accidentally dropped a test-tube rack and broke three of the test tubes while the teacher was in the preparation room. To whom should the student report the accident? Give reasons.
11. When your group is performing an experiment in the laboratory, and one of the students accidentally touches his/her eyes and starts shouting for help, briefly explain how you will render a First Aid to your colleague.
12. What are the main safety considerations and precautions when working with basic chemistry laboratory apparatus?
13. Most of the chemistry laboratory apparatus are made from glass. What could be the reasons behind?
14. Which reasons will you use to convince your friend that a chemistry laboratory must adhere to safety measures?
15. A Form One Student was boiling water on a Bunsen burner without using a wire gauze. If you were to advise him/her, what could be your advice on the necessity of using the wire gauze when using a Bunsen burner in a laboratory setting?
16. Your sister wants to know where your laboratory apparatus skills will be applied in real life. How could you help her using a kitchen as a laboratory setting?

Chapter Three: Fire, Firefighting and Flames

Introduction

In chemistry laboratories, flames from various sources of heat are used for heating purposes. The flames produced should be handled well to ensure safety. When flames are not properly handled can lead to fire accidents. In this chapter, you will learn about fire, firefighting and flames. The competencies developed will enable you to use flames from various sources appropriately and protect yourself, others and the environment from fire accidents both at school and out of school.

Think

The significance of fire in daily life activities and the potential risks of uncontrolled fire.

Fire

Fire is the state at which an ignited material combines with oxygen and gives off light, heat, flame and combustion products. When controlled, fire can be beneficial and used for cooking, heating or industrial processes.

Task 3.1

Search reliable online sources for the components required to start a fire. Then, write a summary describing the role of each component.

Components Needed to Start Fire

For a fire to start, a combination of heat, oxygen and fuel is needed in the suitable proportion. The three components are usually referred to as the fire triangle. If any of them is missing, no fire will start or continue burning.

The Fire Triangle

Three essential components for fire:

• Fuel - Substance that releases energy when burned
• Oxygen - Supports combustion
• Heat - Provides activation energy for combustion

Note: A fuel is a substance that releases energy when burned. Examples of fuels are wood, charcoal, natural gas, kerosene, petrol, diesel and coal.

Task 3.2

Use available resources in your environment to demonstrate the necessity of each component of a fire triangle. Note: The environment should be controlled to ensure safety.

Firefighting

Uncontrolled fires can be dangerous and destructive leading to injuries, property damage and environmental harm. Firefighting is the act of extinguishing fires and mitigating their effects. Materials which are used to put out fires are called fire extinguishers.

Firefighting usually involves eliminating at least one of the three components in the fire triangle. Most firefighting equipment work by cutting off the oxygen supply to the fire to effectively extinguish it. In addition, each type of fire will need appropriate firefighting techniques and materials. The use of a wrong fire extinguisher for a particular fire can result in the fire spreading instead of being put out.

Class	Burning Materials	Appropriate Fire Extinguishers
A	Ordinary solid combustible materials such as paper, wood and clothing	• Use water • Any type of portable fire extinguisher except carbon dioxide
B	Flammable liquids such as petrol, alcohol, kerosene and oil-based paints	• If the fire is small, use a fire blanket or sand • If the fire is large, use dry powder, foam or carbon dioxide extinguisher
C	Flammable gases such as butane and propane	• Dry powder extinguisher • Carbon dioxide extinguisher
D	Combustible metals such as magnesium, sodium and lithium, especially in powder form	• Dry powder extinguisher • Foam extinguisher
F	Cooking oils and fats	• Wet chemical extinguishers

Note: Fires caused by electricity are not given their own full classes as they can fall into any of the classifications. After all, it is not the electricity that burns but the surrounding material that has been set alight by the electric current. Electricity can be a source of any of the fire classes A, B, C, D and F. Normally, the fire caused by an electrical fault is extinguished based on the burning material. Thus, dry powder, carbon dioxide gas and dry sand can be used to extinguish the fire. Before extinguishing the fire caused by an electrical fault, the main electrical switch should be turned off.

Task 3.3

A Form One Student has been using a cooker for several weeks without cleaning. On one occasion while cooking a small fire broke out on the upper surface of the cooker and spread to the nearby curtains.

Questions:

1. Identify the sources of ignition and fuel.
2. What type of fire extinguisher is most suitable for the fire and why?

Portable Fire Extinguishers

A portable fire extinguisher is an equipment used to put out fire and can be easily moved from one place to another. It is usually hung in an upright position in automobiles and on the walls of buildings such as schools and other public buildings. A portable fire extinguisher consists of a metal container that contains the extinguishing agent (substance) stored at high pressure.

Type of Fire Extinguishers	Chemical Composition of Extinguishing Agents	Suitable For	Not Suitable For
Air Pressurised Water (APW)	Ordinary tap water pressurised by air	Class A fire	Fire classes B, C and D (will spread the flame)
Dry chemical (DC)	Fine sodium bicarbonate powder pressurised by nitrogen	Classes A, B and C fires	Aircraft and electronics fires (Corrosive to metals such as aluminium)
Carbon dioxide	Carbon dioxide gas under extreme high pressure	Classes B and C fires and fire caused by electrical faults	Class A fire (material can re-ignite)
Halon	Bromochloro-difluoro-methane	Class A fire and fire caused by electrical faults	Classes B and C fires (least suitable)
Foam	Proteins and fluoro-proteins	Classes A and B fires	Fire caused by electrical faults
Wet chemical	Potassium acetate	Class F fire	Fires caused by electrical faults
ABC	Monoammonium phosphate with a nitrogen carrier	Classes A, B and C fires	Fire on electronic equipment

Note: For small Class A fire (of combustible solids), water can be used to easily put out the flames. Small fires that involve flammable liquids should be put out using sand or fire blanket. These cut off the oxygen supply. Water should never be used to put out Class B (flammable liquids) fires since it would spread the flame. Water is denser than flammable liquids, hence when poured, flammable liquids float above it.

How to Use a Portable Fire Extinguisher

Portable fire extinguishers should be used in the right ways to quickly put out fires. The extinguisher should aim at the base part of a flame.

Steps for Using a Fire Extinguisher:

1. Remove the safety pin
2. Hold the discharge hose and focus at the base of the fire
3. Squeeze the top lever to release the extinguishing agent
4. Sweep from side to side until the fire is extinguished

Precautions

The following precautions should be taken when using portable fire extinguishers:

1. Keep a reasonable distance (at least 1.5 metres) from the fire as it may suddenly change direction.
2. For a person on fire, use a fire blanket instead of portable fire extinguisher.
3. Do not test a portable fire extinguisher at your school without permission.
4. Do not return a used portable fire extinguisher to its place.
5. Do not hold the discharge horn when using carbon dioxide type fire extinguisher as it become extremely cold that can lead to severe frost burns.
6. When a fire gets out of control, abandon it and notify the nearest firefighting squad (fire brigade).

Activity 3.1

Aim: To extinguish small fires using the appropriate fire extinguisher.

Requirements: Sand bucket, portable fire extinguishers such as carbon dioxide and wet chemical fire extinguishers, combustible materials such as kerosene, papers and cooking oil

Caution: Fire can cause accidents; therefore, safety measures must be observed.

Procedure:

1. Light carefully the combustible material. This should be done in outdoors under the supervision of your teacher or laboratory technician.
2. Use the right fire extinguisher to put out the fire.
3. Repeat the steps 1 and 2 using different combustible materials, one at a time.

Question: Why is it important to use the right type of fire extinguisher to put out a fire?

Flames

Task 3.4

Using books from the library and online sources, search for different heat sources that produce flames and write a brief report using the following hints:

1. Types of heat sources commonly used in the laboratory.
2. Types of flames produced by each heat source named in 1.

A flame is a zone or region of burning gases that produces heat and light. It is the visible glowing part of fire. The flame is formed as a result of burning a fuel. The colour and temperature of the flame depends on the type of the fuel used, source of the flame and the oxygen supply.

Flames can be classified depending on the light they produce. Based on this, there are two main types of flames; luminous and non-luminous flames.

Luminous Flame

Color: Bright yellow

Oxygen Supply: Limited

Produces: Soot

Heat: Less hot

Safety: Safety flame (easily seen)

Non-Luminous Flame

Color: Blue

Oxygen Supply: Sufficient

Produces: No soot

Heat: Very hot

Safety: Can cause accidents (not easily seen)

Different heat sources produce different flames. For example, a candle and a spirit lamp produce luminous flames, whereas a gas stove produces a non-luminous flame. However, some of the heat sources can be regulated to produce both types of flames. For instance, a kerosene stove, gas stove and Bunsen burner can be regulated to produce either luminous or non-luminous flame.

Activity 3.2

Aim: To produce different types of flames from different heat sources.

Requirements: Lighter; various heat sources such as charcoal burner; candle, hurricane lamp, kerosene stove, spirit burner; gas stove, tin lamp and the Bunsen burner

Procedure:

1. Light up one heat source after another under the supervision of the teacher. Care should be taken when handling the heat sources.
2. Carefully identify the types of flames produced by the different heat sources.
3. Record your observations in a table.

Question: What are the characteristic features of each type of the observed flames?

Bunsen Burner

A Bunsen burner is a laboratory heat source consisting of a vertical metal tube connected to a gas source. The burner is named after the German chemist, Robert Bunsen, who invented it in 1855. The Bunsen burner is able to produce a very hot flame of temperatures up to 1000 °C from a mixture of gas and air.

Parts of the Bunsen Burner

• Air hole - Adjustable holes for air intake
• Barrel/Chimney - Vertical metal tube
• Collar - Used for air adjustment
• Jet - Where gas enters
• Gas inlet - Connection for gas supply
• Base - Support stand

How the Bunsen Burner Works

Gas enters the burner through a tube connected to a jet inside the base. Air enters the burner through the adjustable air holes. The amount of air coming in can be varied by turning the collar. At the top of the barrel, the mixture of gas and air burns to produce a flame. The type of flame obtained depends on the amount of oxygen available for burning.

• Air holes closed - Less oxygen supply → Luminous flame
• Air holes partly open - More oxygen supply → Medium flame
• Air holes fully open - Enough oxygen supply → Non-luminous flame

Activity 3.3

Aim: To light a Bunsen burner.

Requirements: Matchbox or lighter, wooden splint and Bunsen burner

Caution: Keep your face away from the tip of the barrel when you light the Bunsen burner. You should also not allow gas to come out for long time without lighting the burner as it can lead to serious fire accident.

Procedure:

1. Close the air holes of the burner.
2. Connect the burner to the gas tubing.
3. Light a match or wooden splint and hold it on top of the barrel.
4. Slowly turn on the gas. The gas will light up if the tap is connected properly to the tubing. Ask for your teacher's assistance if it does not light up.
5. Open the air holes halfway and then fully. Record your observations.

Questions:

1. What happened to the flame when you opened the air holes halfway?
2. What happened to the flame when the air holes were fully opened?

Note: Burning back or striking back is an event that occurs when a gas burns at the jet. It occurs when lighting the Bunsen burner while the air holes are open. This can be corrected by turning off the gas supply, then relight the burner.

Parts of Flames

Both luminous and non-luminous flames have different parts.

Flame Type	Parts	Description
Luminous Flame	Thin outer zone	Outermost part of the flame
	Yellow middle zone	Main luminous region
	Inner unburnt zone	Region of unburnt gases
	Blue outer zone	Small blue region at base
Non-luminous Flame	Colorless inner zone	Region of unburnt gas
	Blue-green middle zone	Region where part of gas burns (hottest part at tip)
	Pale purple-blue outer zone	Region of complete burning

Uses of Different Types of Flames

Activity 3.5

Aim: To determine the type of flame that can be used for heating in the laboratory.

Requirements: Matches box or lighter, safety goggles, Bunsen burner, beakers, stopwatch, water, wire gauze and tripod stand

Caution: Before starting the activity, make sure you wear safety goggles and know where the nearby fire extinguishers are located in case of fire accident.

Procedure:

1. Set two beakers of equal amounts of water on Bunsen burners whereby the first beaker is heated by a luminous flame and the second beaker is heated by a non-luminous flame.
2. Start a stop watch immediately after setting the two beakers on the heat sources.
3. Note the time when water starts boiling in each beaker.

Questions:

1. Which beaker started boiling first?
2. Based on the activity performed, what type of flame is suitable for heating in the laboratory? Explain.

Uses of Luminous Flame

Luminous flame is mainly used for lighting because it is bright. It is also not very hot, therefore, it is safer for lighting than the non-luminous flame. Some heat sources such as tin lamp and hurricane lamp produce luminous flame which is mainly used as a source of light and not for the purpose of heating or cooking.

Uses of Non-luminous Flame

The following are some of the ways in which the non-luminous flame is used:

1. The flame is used for heating purposes because it gives a lot of heat. Most heating in the laboratory is done using a non-luminous flame.
2. The non-luminous flame is used in the flame test of certain chemical substances.
3. Non-luminous flame is suitable for welding because it is very hot.
4. A non-luminous flame is suitable for cooking because it gives enough heat and it does not produce soot.

Chapter Summary

1. The components needed to start fire are fuel, oxygen and heat.
2. Fire is the state of combustion in which ignited materials combine with oxygen to give off light, heat, flame and combustion products.
3. Firefighting is the extinguishing of hazardous/harmful fires.
4. A Bunsen burner is the most commonly used source of heat in the laboratory.
5. A flame is a zone or region of burning gases that produces heat and light.
6. There are two main types of flames, the luminous flame and non-luminous flame.
7. The luminous flame is yellow in colour, produces soot and is less hot than non-luminous flame.
8. The non-luminous flame is blue in colour, does not produce soot, and gives more heat.

Revision Exercise 3

1. The following are the steps to follow in lighting the Bunsen burner. However, the steps are not in the correct order. Re-write them in the correct sequence.
   (a) To extinguish the flame, turn off the gas tap to stop the gas flow.
   (b) Light the gas at the top of the barrel with a lighted match stick.
   (c) Turn the collar to close the air hole completely.
   (d) Keep your face away from the top of the barrel.
   (e) Adjust the gas tap until the supply of gas is enough for a flame.
   (f) Turn on the gas fully to ensure that plenty of the gas enters the burner.
2. Write TRUE for a correct statement and FALSE for an incorrect statement. Give a reason for your answers.
   (a) A yellow flame is obtained when the air holes of the Bunsen burner are open.
   (b) When the air holes are completely closed, a Bunsen burner produces a non-luminous flame.
   (c) The safety flame of a Bunsen burner is the hottest part of the flame.
   (d) A quiet flame is obtained when the air holes of the Bunsen burner are completely open.
   (e) The yellow colour of a luminous flame is due to the presence of hot carbon particles.
   (f) A non-luminous flame looks similar to a candle flame.
   (g) Controlling the fuel gas flow allows one to change the flame colour of a gas burner.
   (h) The dark zone of a luminous flame consists of unburnt gas.
   (i) The hottest part of a non-luminous flame is just over the tip of the dark zone.
   (j) Understanding fire triangle is fundamental in fire safety.
3. Students went to camp in an isolated area where they needed to make tea using a portable stove. Which type of flame would be selected, and what are the practical reasons behind their choice?
4. What determine the choice of an appropriate firefighting equipment in the event of fire accidents?
5. What are some common problems that could arise when using a Bunsen burner, and what solutions would you recommend?
6. Why is it not advised to use water for extinguishing Class B fire and the fire caused by electrical faults?
7. A student was preparing food for the family by a deep-frying method. Accidentally, the cooking pan tipped over and a huge fire spread on the kitchen floor.
   (a) Identify the fuel in this fire accident.
   (b) Which fire extinguishers would be suitable for putting out the fire? Explain.
8. If a gas cooker is involved in a fire accident, what steps can be taken to extinguish the fire safely?

Chapter Four: Matter

Introduction

The entire universe is composed of matter. Matter is the substance that makes up everything in our environment, including ourselves, water, air, metals, plants and animals. An understanding of matter creates the way for understanding its nature and how it can be used. In this chapter, you will learn about the states of matter; as well as physical and chemical changes of matter. The competencies developed will enable you to use the changes of states of matter to get solutions to daily challenges in life.

Think

Various processes in daily life that involve changes in states of matter.

States of Matter

Task 4.1

1. Watch videos or simulations showing how particles are arranged in different states of matter.
2. Relate the arrangement of the particles observed with the properties of matter found in your environment.

Matter can exist in different states such as solid, liquid and gas. Plasma is often called the fourth state of matter distinct from the more commonly encountered solid, liquid and gas state. The mentioned states are referred to as fundamental states of matter because they are observable in everyday life and are defined by their volume, shape and the general properties of the substances. The state of matter depends largely on the changes in temperature and pressure.

Solids

Properties:

• Definite shape
• Definite volume
• Particles closely packed
• Vibrate in fixed positions

Examples: Stones, firewood, cooking pots, pencils

Liquids

Properties:

• Indefinite shape
• Definite volume
• Particles can slide past each other
• Takes shape of container

Examples: Juice, milk, water

Gases

Properties:

• Indefinite shape
• Indefinite volume
• Particles far apart
• Expand to fill container

Examples: Oxygen, hydrogen, carbon dioxide

Plasma

Properties:

• Charged particles
• Very high temperature
• Conducts electricity
• No definite shape or volume

Examples: Stars, lightning, plasma TVs

The solid, liquid and gas states are composed of particles namely atoms whereas a plasma state is composed of charged particles. The liquids, gases and plasma states of matter are classified as fluids because their particles have ability to flow due to their constant random motion.

Activity 4.1

Aim: To investigate the properties of matter.

Requirements: Beakers, analytical balance, stones, pieces of chalk, pieces of wood, metals, papers, balloons and liquids such as water, milk and ink

Procedure:

1. Collect different items like stones, pieces of chalk, papers, water, milk, ink and balloons.
2. Carefully observe all the objects you have collected. Use your sense of sight to make your observations on size and shape.
3. Take two beakers, label them as A and B, weigh each beaker and record its mass.
4. Fill Beaker A with water and re-weight it. Record the mass and the volume of water.
5. Fill Beaker B with milk and re-weight it. Record the mass and volume of milk.
6. Weigh the solids, one at a time and record the mass of each solid.
7. Take the solids, one at a time and dip them into the beaker filled with water.
8. Record the volume and mass of water displaced.
9. Weigh a balloon that is not inflated and record its mass.
10. Blow air into the balloon and record its mass.

Questions:

1. Do all the substances have mass? Explain.
2. Give reasons why the solids displace some water in the beaker.

Changes in States of Matter

Matter may change from one state to another. For example, when heated some solids melt to become liquids, while liquids change into gases (vapour) and vapour changes to plasma under high temperature. In some cases, the reverse changes take place.

Inter-conversion of States of Matter

Solid

⇄

Liquid

⇄

Gas

⇄

Plasma

Processes: Melting/Freezing ↔ Vaporization/Condensation ↔ Ionization/Deionization

Melting and Freezing

Melting is a process in which a substance changes from a solid to a liquid. When a solid is heated, the particles gain energy and vibrate fast. Eventually, they break free from their fixed positions and begin to move in clusters. The temperature at which a solid change to liquid at standard atmospheric pressure is called melting point.

Freezing is the process in which a substance changes from a liquid to a solid. The temperature at which a liquid change to solid is called freezing point. The freezing point of pure water is 0 °C, which is also the melting point of ice.

Vaporization and Condensation

Vaporization is the conversion of a substance from a liquid to a vapour. When the liquid is heated, the particles move faster as their average kinetic energy increases. Some of the particles at the surface of the liquid gain enough kinetic energy and escape into the air. As more of the liquid particles escape to form a gas, the liquid is said to evaporate.

The temperature at which the vapour pressure of the liquid is equal to the atmospheric pressure is called the boiling point. When a vapour is cooled, the average kinetic energy of the particles decreases and the particles come closer. The forces of attraction between the particles become significant and cause the vapour to condense into a liquid. This process is called condensation.

Sublimation and Deposition

Sublimation occurs when a solid is heated and changes directly into a gas. In sublimation, a solid does not pass through the liquid state, instead it changes directly into a gas. The direct change of a gas to a solid is called deposition. In sublimation and deposition, the liquid state is bypassed.

Ionization and Deionization

These are the processes involved in the formation and deformation of plasma. When a gaseous state of matter is subjected to a very high temperature, the atoms that form gases gain more kinetic energy, collide with each other and hence lose their electrons to become free ions. This process is called ionization.

On the other hand, deionization refers to the recombination of free ions and electrons of the plasma to form atoms that eventually combine to form gas molecules. This occurs when temperature decreases in the system.

Activity 4.2

Aim: To investigate the changes of matter from one state to another.

Requirements: Watch glass, source of heat, beaker and ice cubes

Procedure:

1. Put some ice cubes in a beaker and heat. Carefully observe the changes that take place.
2. Heat the substance further until it starts to change into vapour.
3. Cover the beaker with a watch glass.
4. Carefully remove the watch glass and record your observations on the surface of the watch glass.

Questions:

1. What was the shape of the ice before heating?
2. What was the shape of the substance formed after heating the ice?
3. What happened when water was heated above its boiling point?
4. What happened after covering the heated substance in a beaker with the watch glass?

Importance of the Changes in States of Matter

Task 4.2

Watch videos illustrating the importance of the changes in states of matter and write a summary of what you have learnt.

Applications of State Changes:

• Water Cycle - Describes continuous process that drives movements of water on, above, and below Earth's surface
• Refrigeration - Uses refrigerants whose change in state involves changes in energy, causing cooling effect
• Refinery - Petroleum and distillery work under principle that liquids can change to vapour and back
• Metallurgy - Involves extraction and purification of metals; changes from solid to liquid and back make it possible
• Steam Engines - Use steam as working fluid; change from liquid water to steam makes operation possible
• Drying of Materials - Occurs when liquid changes to vapour
• Production of Electricity - Coal heats water into vapour to drive turbines

Particulate Nature of Matter

For a long time, matter was thought to be continuous and lack discrete particles. Later, it was discovered that matter is made up of particles. This was proved by a phenomenon known as the Brownian motion which can be observed in liquids and gases.

The Brownian Motion

In 1827, a botanist called Robert Brown observed through a microscope that pollen grains suspended in water move short distances in an irregular zigzag manner. This is because they are constantly bombarded by water particles. This shows that matter is particulate in nature.

Other examples which show that matter is made up of particles that are in constant motion include:

• The spread of the smell of food being cooked from kitchen to considerable distance
• Diffusion of potassium permanganate particles in water
• The spread of perfume due to diffusion of perfume vapours into the air

Diffusion is the movement of particles from an area of high concentration to that of low concentration.

Activity 4.3

Aim: To demonstrate Brownian motion.

Requirements: Pollen grains, distilled water, light microscope, microscope slide and dropper

Procedure:

1. Put a drop of distilled water on a microscope slide.
2. Put some pollen grains on top of the drop of water.
3. Place the slide under a microscope and observe any movement of the pollen grains.

Questions:

1. Is the movement patterned or random?
2. Why do the pollen grains move in this manner?

Kinetic Nature of Matter

Task 4.4

Watch the simulation demonstrating the kinetic nature of matter. Observe how the particles move. Compare the motion of particles in solid, liquid and gas with their properties.

The particles of matter tend to display different characteristics depending on the physical state of the substance.

Kinetic Molecular Behavior

Solids: Particles are packed closely together that they can only vibrate but not move. The more energy they have, the more they vibrate.

Liquids: Particles are still close together but they have no definite order. However, the particles in liquids have some spaces between them and can move around or slide past each other.

Gases: Particles are far apart from each other with no regular order. The large spaces between the gas particles make gases compressible.

Plasma: Particles are in charged forms (positive and negative) and scattered.

Property	Solid	Liquid	Gas	Plasma
Shape	Retains a fixed shape	Takes the shape of its container	Has no definite shape, fills the shape of container	Has no definite shape, fills the shape of container
Volume	Has a fixed volume	Has a fixed volume	Takes the volume of its container	Takes the volume of its container
Movement of particles	Particles vibrate in fixed positions	Particles move or slide past each other	Particles move freely and randomly	Highly energetic, charged particles move randomly
Compressibility	Not compressible	Slightly compressible	Highly compressible	Compressible

Physical and Chemical Changes

Physical Changes

Physical changes are changes that affect only the physical properties of matter. They do not result in the formation of new substances. Examples include:

• Melting of ice
• Boiling of water
• Dissolving salt in water
• Crushing a can
• Cutting paper

Physical changes are usually reversible.

Chemical Changes

Chemical changes are changes that affect the chemical properties of matter and result in the formation of new substances. Examples include:

• Burning of wood
• Rusting of iron
• Cooking food
• Digestion of food
• Fermentation

Chemical changes are usually irreversible.

Activity 4.8

Aim: To demonstrate conditions necessary for rusting of iron nails.

Requirements: Iron nails, oil, cotton wool, four test tubes, water and anhydrous calcium chloride

Procedure:

1. Label four dry test tubes, A, B, C and D.
2. Put two new iron nails in each test tube.
3. Insert some cotton wool in Test tube A and add about 5 cm³ of tap water to make the cotton wool wet.
4. Add about 10 cm³ of boiled tap water to test tube B followed by 3 cm³ of oil.
5. Insert some cotton wool in test tube C and place some crystals of anhydrous calcium chloride on the cotton wool.
6. Do not put anything in test tube D except nails.
7. Leave the set-up open to the air for three days.

Questions:

1. What are the observations in the test tubes after three days?
2. Why was boiled water and oil added in Test tube B?
3. What was the function of anhydrous calcium chloride in Test tube C?
4. From the results of the experiment, state the conditions necessary for rusting to occur.

Physical Changes	Chemical Changes
Affect only physical properties of matter	Affect both physical and chemical properties of matter
Are temporary changes	Are permanent changes
Are easily reversible which means the original substance can be recovered	Are irreversible which means the original substance cannot be recovered
No new substance is formed	New substances are formed
The molecules are rearranged while their actual compositions remain the same	The molecular compositions of a substance completely change
No energy is produced or absorbed	Energy is produced or absorbed

Chapter Summary

1. Matter is anything that has mass and occupies space.
2. Matter exists as solid, liquid, gas and occasionally as plasma.
3. A solid is a substance that does not flow easily and retains its shape and size.
4. A liquid is a substance that flows, retains its volume but takes the shape of the container in which it is held.
5. A gas is a substance that has neither definite shape nor size.
6. Plasma is a charged gas that occurs when the gas is extremely heated.
7. Sublimation is the change of state of matter from a solid state directly to a gas or vapour without passing through a liquid state.
8. Matter is made up of particles that are able to display some forms of movements.
9. Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
10. Brownian motion refers to the random movements of particles suspended in a liquid or gas.
11. The kinetic molecular behaviour is the way particles behave in solids, liquids and gases.
12. Physical changes are reversible. They only affect the physical properties of substances, such as shape and state.
13. Chemical changes are irreversible. They affect the chemical properties of substances.
14. A chemical change results in the production of new substances while a physical change does not.

Revision Exercise 4

1. What types of changes are these?
   (a) Cloud changing into rain
   (b) Magnetising of iron
   (c) Heating an iron rod
   (d) Rotting of mangoes
   (e) Decaying of teeth
2. A Form One Student has a balloon filled with a certain gas. If the student puts the balloon in the freezer overnight, what do you think will happen to the balloon? Explain.
3. When a container of coffee is opened in a room, people in different parts of the room may notice its smell. Explain.
4. Describe the role of changes in state of matter in water purification.
5. Explain how the changes in state of matter are linked to the formation of rain cloud in areas of low pressure and moist air.
6. How does temperature affect the state of matter?
7. Give four real-life examples that illustrate the kinetic nature of matter.
8. Explain how physical and chemical changes are involved in cooking process.
9. When a metal such as copper is heated, it expands. Explain what happens to the metal particles during expansion.
10. Explain how physical and chemical changes are involved in steel production and food processing industries.

Chapter Five: Elements, Compounds and Mixtures

Introduction

Everything in the universe is composed of one or more elements. Elements are the building units of compounds. When compounds combine physically, they form mixtures. In this chapter, you will learn about elements and their chemical symbols, binary compounds and mixtures, and separation of mixtures. The competencies developed will enable you to identify and classify substances which are useful in your daily life activities, regain useful pure substances out of impure substances, and make compounds and mixtures for day-to-day needs.

Think

The building blocks of all materials in the universe.

Elements and Chemical Symbols

Task 5.1

1. Watch animations showing different elements and write the meaning of element.
2. How are elements commonly written?

A limitless number of words can be written using the letters of the alphabet, which are the building blocks of all the words. Most of buildings are made by different bricks. The bricks are the building blocks of the buildings.

Task 5.2

1. Take a piece of chalk. Note its size.
2. Break the piece of chalk into two halves, note the size of each piece. Compare the size of the pieces to the original chalk.
3. Take the two halves of pieces of chalks and continue breaking them into halves until you can no longer break them.

Questions:

1. How does this task help you to understand the concept of element?
2. Why is it difficult to break the pieces of chalk further?

Matter is made up of tiny particles called atoms which are the smallest particles of a chemical elements that can exist. An element is a pure chemical substance which cannot be split into simpler substances by a simple chemical process. There are 118 known chemical elements, most of which occur naturally, while few are man-made.

Sodium Metal

Symbol: Na

Soft, silvery metal

Carbon

Symbol: C

Exists as diamond, graphite

Gold

Symbol: Au

Precious yellow metal

Copper

Symbol: Cu

Reddish-brown metal

Names and Chemical Symbols of Elements

Elements have names that are usually represented by letters, commonly known as chemical symbols. The chemical symbols are abbreviations or short representations of element names. The use of symbols has made it easier for chemists, other scientists and students in studying chemistry and other sciences.

Chemical symbols are often derived from the Latin or Greek names of the elements and may not have much similarity to the common English names. For example, the symbol for sodium is Na which is derived from the Latin name Natrium and the symbol for gold is Au which is derived from the Latin name Aurum. Chemical symbols are written according to the rules of the International Union of Pure and Applied Chemistry (IUPAC).

Criteria for Assigning Chemical Symbols

Name	Chemical Symbol	Derivation
Boron	B	First letter of English name
Carbon	C	First letter of English name
Fluorine	F	First letter of English name
Aluminium	Al	First two letters of English name
Calcium	Ca	First two letters of English name
Sodium	Na	From Latin name Natrium
Gold	Au	From Latin name Aurum
Iron	Fe	From Latin name Ferrum
Lead	Pb	From Latin name Plumbum
Mercury	Hg	From Latin name Hydrargyrum

Metals and Non-metals

Metals

• Good conductors of electricity
• Good conductors of heat
• High melting and boiling points
• High tensile strength
• Sonorous (produce sound when hit)
• Ductile (can be drawn into wires)
• Malleable (can be hammered into sheets)
• Lustrous (shiny surfaces)

Examples: Iron, copper, aluminium, gold, silver

Non-metals

• Poor conductors of electricity
• Poor conductors of heat
• Low melting and boiling points
• Low tensile strength
• Not sonorous
• Not ductile
• Not malleable
• Non-lustrous (except diamond)

Examples: Carbon, sulfur, oxygen, nitrogen

Task 5.4

Collect the following materials: aluminium wires, copper wires, iron nails, charcoal, roll sulfur and zinc strips. Describe each material in terms of:

1. Appearance
2. Malleability
3. Tensile strength
4. Sonority

Compounds and Mixtures

A compound is a pure substance made up of two or more elements in a chemical combination. When a compound is made up of two components is referred to as a binary compound. Examples of binary compounds include carbon dioxide gas, common salt and water.

First Part	Second Part	Compound
Sulfur	Oxygen	Sulfur dioxide
Sodium	Chlorine	Sodium chloride (common salt)
Hydrogen	Oxygen	Water
Nitrogen	Hydrogen	Ammonia
Zinc	Sulfur	Zinc sulfide

Properties of Binary Compounds

1. The components in it have different properties from those of the resulting compound.
2. Whenever a compound is formed the substances in it combine in definite proportions.
3. A compound is formed only by a chemical reaction.
4. The components of a compound can only be separated by chemical means.

A mixture is a physical combination of two or more substances in any ratio. Since mixtures are not chemically combined, they can be separated by physical means. The mixtures can be liquid-liquid (for example, oil and water), solid-liquid (for example, muddy water) or solid-solid (for example sand and salt).

S/N	Mixture	Compound
1.	The components can be separated from one another by physical methods	The constituent elements cannot be separated by physical methods but can be separated by chemical methods
2.	Mixtures may vary widely in compositions. The components are mixed in any proportions	Compounds have always definite/fixed compositions by mass of the elements. The proportions are fixed
3.	No chemical change occurs when mixtures are formed	Chemical changes are involved when compounds are formed
4.	The properties of mixtures are those of the individual components	The properties of compounds are very different from those of the individual elements

Activity 5.1

Aim: To compare the properties of a mixture and a compound.

Requirements: Test tubes, stoppers, test tube rack, mortar and pestle, burner, retort stand and clamp, spatula, sheets of paper, powdered sulfur, magnet, coarse and fine powdered iron filings, dilute hydrochloric acid and an analytical balance

Caution: The gas being produced is poisonous in high concentrations, smell it by wafting it towards your nose.

Questions:

1. Describe what takes place when a magnet is placed near a mixture of sulfur and iron.
2. What happens when dilute hydrochloric acid is added to a test tube containing a mixture of iron and sulfur?
3. What happens when a magnet is placed near the cooled product formed when the mixture of iron and sulfur is heated? Explain your answer.
4. What type of change takes place when dilute hydrochloric acid is added to the product formed when the mixture of iron and sulfur is heated?

Solutions, Suspensions and Emulsions

Solutions

Definition: Homogeneous mixture of solvent and solute

Properties:

• Transparent/clear
• Solute particles completely dissolved
• Components separated by evaporation

Examples: Salt water, sugar water

Suspensions

Definition: Heterogeneous mixture of liquid and fine solid particles

Properties:

• Opaque/not clear
• Solute particles settle if undisturbed
• Components separated by filtration

Examples: Muddy water, medicine syrups

Emulsions

Definition: Mixture of immiscible liquids

Properties:

• Formed from oil and water-based liquids
• Appears homogeneous when shaken
• Separates into layers when left standing

Examples: Milk, emulsion paint

Separation of Mixtures

Task 5.7

Watch videos demonstrating different methods used for separation of mixtures. Identify the methods presented and relate them with those used in your daily life.

Many mixtures contain useful substances mixed with unwanted materials (impurities). In order to obtain the useful substances, chemists often separate the mixtures using different methods. The separation method depends on the components of the mixture and their properties.

Common Separation Methods

Decantation

Principle: Separating heterogeneous mixture of liquid and solid by pouring out liquid

Used for: Muddy water, mixtures with large solid particles

Process: Let mixture stand, pour off clear liquid

Filtration

Principle: Separating solid from liquid using porous filter

Used for: Sand and water, insoluble solids in liquids

Apparatus: Filter paper, filter funnel, conical flask

Evaporation

Principle: Separating solute from liquid solution through heating

Used for: Salt water, solutions where solute doesn't decompose

Apparatus: Evaporating dish, Bunsen burner

Distillation

Principle: Separating components by heating to vaporize and then condensing

Types: Simple distillation, fractional distillation

Used for: Purifying water, separating miscible liquids

Chromatography

Principle: Separating mixtures using solvent and immobile substance

Types: Paper chromatography, thin layer chromatography

Used for: Separating pigments, analyzing drugs

Simple Distillation Setup

Used for separating liquids from solutions or purifying water

Components: Distilling flask, thermometer, Liebig condenser, receiving flask

Activity 5.12

Aim: To carry out simple paper chromatography.

Requirements: Filter paper, beakers, extracts from plant parts such as leaves, roots or stem bark, acetone or ethanol, droppers and watch glass

Questions:

1. What is the role of the acetone or ethanol in this experiment?
2. Can the type and quality of paper influence the separation results? Explain.

Uses of Chromatography

Biology

• Protein analysis
• Enzyme analysis
• Plasma analysis

Chemistry

• Testing purity
• Separate mixtures
• Composition analysis

Health & Environment

• Water pollution testing
• Food contamination
• Soil analysis

Security

• Crime scene analysis
• Drug testing
• Fiber detection

Medicine

• Blood cell study
• Drug detection
• Medical research

Industries

• Quality testing
• Shelf-life analysis
• Purification

Chapter Summary

1. An element is a pure substance that cannot be broken into simpler substances by ordinary chemical means.
2. Chemical symbols are representations of the names of elements using letters.
3. The first letter of the chemical symbol must always be a capital letter.
4. Elements that have identical first letters are usually differentiated by a second or a third letter.
5. Chemical symbols are derived from the Latin names or Greek names of the elements and some English names.
6. A compound is a pure substance made up of two or more elements in a chemical combination.
7. A mixture is a physical combination of two or more substances in any proportion.
8. A solution is a homogeneous mixture composed of a solute dissolved in a solvent.
9. A suspension is a heterogeneous mixture of liquid and fine solid particles.
10. The methods of separating mixtures are determined by the components of interest.
11. Liquid-solid mixtures can be separated by evaporation, decantation, distillation or filtration.
12. Liquid-liquid mixtures can be separated using fractional distillation, separating funnel, or chromatography.
13. Solid-solid mixtures can be separated using a variety of methods such as using a magnet, sublimation, by using a suitable solvent and by winnowing.

Revision Exercise 5

Choose the correct answer in items 1-8.

1. The chief cook added sugar to the cup of coffee. The resulting solution can be termed as:
   (a) Homogenous mixture
   (b) Binary compound
   (c) Heterogeneous mixture
   (d) Uniform suspension
2. Your young brother was given a syrup with a prescription that it should be well shaken before use. This is because the syrup is a:
   (a) clear solution.
   (b) suspension.
   (c) homogeneous mixture.
   (d) filtrate.
3. Table salt in water makes a homogenous mixture. What is the kind of the resulting mixture?
   (a) Solute
   (b) Solvent
   (c) Suspension
   (d) Solution
4. Which of the following is a compound?
   (a) Helium (He)
   (b) Hydrogen (H₂)
   (c) Carbon monoxide (CO)
   (d) Neon (Ne)
5. An element is defined as a:
   (a) pure substance made up of two or more types of atoms.
   (b) substance composed of multiple elements.
   (c) substance composed of identical atoms.
   (d) mixture of compounds.
6. Which of the following is a heterogeneous mixture?
   (a) Saltwater
   (b) Air
   (c) A fruit salad
   (d) Vinegar
7. The components of a mixture of iron and sand can be separated by:
   (a) Boiling
   (b) Filtration
   (c) Chemical reaction
   (d) Magnetic attraction
8. Which process among the following is involved in decantation?
   (a) Sedimentation
   (b) Melting
   (c) Saturation
   (d) Distillation
9. Write TRUE for a correct statement and FALSE for an incorrect statement.
   (a) A magnet can be used to separate metals from non-metals.
   (b) An unsaturated solution is the one in which the solvent has less than the maximum amount of solute that can dissolve at a given temperature.
   (c) Solutions can only be in liquid form.
   (d) You can obtain sugar crystals from a solution by decantation.
   (e) Ethanol and water are miscible.
   (f) Sublimation is the process by which a substance changes from a solid to a liquid form.
   (g) Emulsion is a clear solution.
   (h) Distillation is a process of separating a mixture of substances with different boiling points.
   (i) A compound is a pure substance made up of two or more elements in a chemical form.
   (j) The first letter of the chemical symbol must be a capital letter.
10. Name the process that can be used to separate each of the following substances:
    (a) Iodine and sand
    (b) Kerosene and water
    (c) A mixture of petrol and diesel
    (d) Components of the stem bark extract
    (e) Oil from seeds
11. Briefly explain how you can differentiate a solution and a suspension by their appearance.
12. What role does the knowledge on boiling point play in distillation process?
13. What factors determine the choice of a specific separation method for a given mixture?
14. Suppose you are given a mixture and you are asked to determine whether it is homogeneous or heterogeneous.
    (a) What could be your criteria for the analysis?
    (b) Make a description of how you will separate the;
    (i) homogeneous mixtures.
    (ii) heterogeneous mixtures.
15. How are suspensions utilised in the food and beverage industry?
16. Provide examples of how chromatography is used in the analysis of pharmaceuticals
17. Describe the applications of solutions, suspensions, and emulsions in daily life.
18. The time taken for sugar to dissolve in cold tea differs from that in hot tea. Explain