Chemistry Book Form one

 TOPIC 1: INTRODUCTION TO CHEMISTRY

The Concept of Chemistry

Chemistry is a branch of science that deals with the study of nature, properties and compos

ition of matter. Matter can be defined as anything that has weight or mass and can occupy space. Therefore, in chemistry we study materials that make up the earth and universe. These range from living to non-living materials. We apply the knowledge of chemistry to study the composition, behavior and nature of materials around us. This study enables us to make the best use of these materials to improve our welfare.

Note:

A person who study chemistry is called chemist

Materials Objects Made by Application of Chemistry

Chemistry is such an important subject that it is applied in other fields such as agriculture, manufacturing, medicine, processing and food industries, education, cosmetics and home care industries, etc. All these industries are responsible for the production of materials that we need to support and hence improve our lives. Materials made by the application of chemistry knowledge include soap, chalk, shoes, clothes, petroleum products, alcoholic and non-alcoholic beverages, cosmetics, drugs, and many others. Can you mention some of the materials made by the application of chemistry knowledge?

This, therefore, means that chemistry is applied in factories, homes, hospitals, pharmacies, research centers, higher learning institutions, etc.

Many products made by the application of chemistry in industry are all around us. Some of these materials are as follows: -

Some products made by application of chemistry

            Field where applied with its examples, of products

·         Medicine, example.  Drugs, vaccines, nutritional supplements

·         Manufacturing industry, example. Vehicles, cement, plastics, chemicals, paints, iron sheets, vanishes, glue

·         Food and beverage industry example.  Soft and alcoholic drinks, baked food, canned food, spices, cooking oil, salt

·         Home care and cosmetics industry example. Cosmetics, detergents, toothpaste, shoe polish, insecticides, antiseptics, disinfectants

·         Transport example.  Fuels, lubricants, oil, grease, tar, coolants, tires

·         Textile industry example, Clothes, dyes, bleaches, wax, threads

·         Leather industry example, Shoes, handbags, belts, leather article

The importance of chemistry in life

Areas Where chemistry is Applied

All these materials, among others, are made by applying chemical processes. They are needed for a better living. Can you mention more materials made through chemistry knowledge?

Some materials made by application of chemistry Nature is made of materials that may be useless, less useful and even harmful. There are also things that are very useful to our lives. Through chemistry, we are able to transform (change) various materials chemically or physically into forms or products that are more useful to man

For example, most laboratory chemicals you use at school are prepared from minerals that are mined from the rocks in the earth. Diagram.

                                   Figure: 01

In everyday life, we need different substances to meet our basic human needs like food, shelter, clothing, comfort and health. Application of chemical knowledge enables the production of different materials and products that we need to live better.

Examples of these materials, as mentioned early, are (paraffin), sugar, common salt, soft drinks, medical drugs (medicines), toothpaste and plastics. Others are spirits, wines, shoe polishes, cement, baking soda, petrol, diesel and cosmetics (soaps, body oils and lotions, body and hair creams, etc.

Some materials made by application of chemistry

Nature is made of materials that may be useless, less useful and even harmful. There are also things that are very useful to our lives. Through chemistry, we are able to transform (change) various materials chemically or physically into forms or products that are more useful to man

For example, most laboratory chemicals you use at school are prepared from minerals that are mined from the rocks in the earth.

Laboratory chemicals

Man cannot use most substances unless they are transformed into products that are more useful. Limestone lying idle in earth is useless until it undergoes deliberate physical and compositional transformation into cement. The cement is used for construction of buildings, roads, bridges and many different structures.

We also need to change different mineral ores through a number of processes into useful substances such as steel, aluminum, tin, etc. Man has learned how to change harmful substances into useful products since the long ago.

Common salt may be made from two hazardous substances–hydrochloric acid and sodium hydroxide.

Chemistry is all around us. We often use chemical products and engage ourselves in chemical processes more than we can tell. Look at the picture below.

This is an example of a chemical activity in which we can engage ourselves without knowing.

                                   Figure :02        

Many items we use at school, home and industry are made by applying chemical processes. The soap we use to wash our clothes and clean our bodies is made from animal fat and an alkali. Many items are made from plastic. Many kinds of plastics are made from crude oil. What items are made from plastics in your home? Soft drink bottles are made from glass. The major component of glass is sand. Glass is made by mixing sand with metal oxides in a furnace at high temperatures. Some clothing is made from natural fibers such as cotton or silk.

Other fabrics like polyester and nylon are made from chemicals found in coal and crude oil. What are your clothes made of?

Clothes made from cotton fibers

Man has used medicines extracted from plants and animals since the beginning of time. For example, cinchona tree contains quinine, which has a bitter taste. Quinine was and is still used for treatment of malaria. Penicillin is extracted from a fungus called penicillin. Nowadays, it is possible to make chemicals that have the same effects as naturally occurring drugs.

This forms the basis of the pharmaceutical drugs industry. What medicines extracted from plants and animals are used in your school or local dispensary?

Injection drugs and vaccines are made from plant or animal extracts

Apart from clothing, it is a tradition to put on shoes and other attire. Rubber shoes are made from rubber. Rubber is a sticky milky fluid obtained from certain tropical trees. Skin shoes and handbags are made from skins and hides of animals. The process of converting these raw materials into the items mentioned above involves chemistry knowledge.

What other items made by chemical processes do you know?

Skin Shoes

Sustainable crop and animal production is also enhanced by application of chemistry knowledge. The use of chemicals in agriculture is inevitable. Fertilizers, insecticides, acaricides, herbicides (weed killers) have and are still playing a good role in agricultural and animal production. In some ecological zones, in order to get good harvest, fertilizer, herbicide and insecticide application is necessary. The same case applies to animal production. As regards to control and prevention of tick-borne diseases, application of different acaricides is often stressed. Also is the use of different drugs to treat internal parasites such as worms, and vaccines to prevent certain diseases.

The Importance of Chemistry in Daily Life

State the importance of Chemistry in daily life

There are a number of reasons for studying chemistry. If you ask someone to tell you the reason for studying chemistry, he/she will give reasons based on how the subject touches him/her. However, there are general and universal reasons as to why we should devote our valuable time and energy to the study of chemistry. In general, we study chemistry because it helps as to understand:

the composition of materials around us;

the nature, properties and behavior of these materials;

why and how materials behave as they do;

how a new material, based on the known properties of its allies or counterparts might behave;

how to make new materials which will be useful to us; and

how to extract and use materials from the earth to improve our welfare.

In economic and occupational terms, we can say that the knowledge of chemistry helps us:

to produce professionals in different disciplines such as pharmacy, engineering, medical and natural science professions; and

make items, goods and materials for sale such as chemical laboratory equipment’s and reagents, medicines, rubber, cement, paints, steel, plastics, etc. What other materials do you think can be included in the list?

Therefore, we can summarize that the study of chemistry is important for survival, development and welfare of man as well as sustainable production of crops and animals.

 TOPIC 2: LABORATORY TECHNIQUES AND SAFETY 

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

·         a room with enough space for carrying out scientific experiments;

·         a store for keeping laboratory apparatus, chemicals and reagents;

·         an office for laboratory technician to sit in and design scientific experiments;

·         enough ventilation to let in fresh air and light;

·         wide doors and several exits for emergency evacuation in case of an accident; and

·         a wide table in front of the laboratory room, fitted with sinks for experiment demonstrations by the teacher or technician.

Rules and safety precautions in a chemistry laboratory for users: -

laboratory Rules:

·         Do not enter the laboratory without permission from your teacher or laboratory technician.

·         Wear safety goggles all the time while in the laboratory. Obey this rule whether you are actually working on an experiment or simply writing in your laboratory notebook.

·         Contact lenses are not allowed. Even when worn under safety goggles, various fumes may accumulate under the lens and cause serious injuries or blindness.

·         Put on closed shoes and trousers when in the laboratory. Sandals and shots are strictly prohibited.

·         Never walk or run unnecessarily in the laboratory.

·         Tie back long hair when using open flames.

·         Eating, drinking, and smoking are strictly prohibited in the laboratory.

·         Don’t perform any experiment not authorized by your teacher or lab technician. If you are curious about trying a procedure not covered in the experimental procedure, consult your teacher or laboratory technician.

·         Never taste anything. Never directly smell the source of any vapour or gas; instead drift a small sample to your nose. Do not inhale this vapour directly but take in only enough to detect an odour if one exists.

·         Always wash your hands after experiments.

·         Never use your hands to transfer chemicals. Use a spatula instead.

·         Notify your teacher or technician immediately in case of an accident

·         Know what chemicals you are using, carefully read the label twice before taking anything from the reagent bottle. Do not interchange labels.

·         Excess reagents are never to be returned to stock bottles. If you take too much, dispose of the excess.

·         Many common reagents, for example, alcohol, acetone and carbon disulphide are highly flammable. Do not use them anywhere near open flames.

·         Pour more concentrated solutions into less concentrated solutions to avoid violent reactions. For example, always add acid to water; not water to acid. If you pour water into acid instead, the heat of reaction will cause the water to explode into steam, sometimes violently, and the acid will splash.

·         If chemicals accidentally splash onto your skin or eyes, flush immediately with plentiful amounts of water and report to your teacher or lab technician.

·         Never eat or drink from laboratory glassware.

·         Never use broken or chipped glassware. If glassware breaks, inform your teacher and dispose of glassware in the litter bin.

·         Keep all windows open for proper ventilation.

·         In case of a gas leakage, turn off the gas tap and open the windows. Leave the room immediately.

The Safety Measures for a Chemistry Laboratory

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

·         Never store food in a refrigerator or freezer where hazardous chemicals are stored. Also, do not eat anything you find in the laboratory or in the laboratory freezer or refrigerator.

·         Make sure fire extinguishers are in good condition. Report any broken seals, damage, low gauge pressure or improper mounting to the teacher or laboratory technician. If the seal has been broken, assume that the fire extinguisher has been used and must be recharged. (Note: Do not use fire extinguishers unless you are trained and feel confident to do so).

·         Be familiar with the location, use and limitations of the safety devices. This includes fire extinguishers, fire blankets, fume hood, spill cleanup materials, first aid kit, eyewash stations and fire alarm.

·         If experiments must be left unattended, place a note next to experimental apparatus indicating the chemicals involved, your name and telephone number on which you can be reached in case of an emergency.

·         Keep the laboratory floor clean and dry at all times. Clean spills of water or chemicals immediately. Then notify other laboratory workers of potential slipping hazards

·         Keep all chemicals in properly labelled containers. This will prevent accidental use of the wrong chemical for a particular experiment.

·         Be familiar with the appropriate safety measures to take when exposed to different hazardous materials. Information is available from your teacher or laboratory technician.

·         All chemicals that react with each other must be stored separately.

·         Be aware of the interaction of laboratory furniture and equipment with chemicals used or stored in the laboratory. For example, oxidizers should not be stored directly on wooden shelves.

·         Use fume hoods/cupboards/chambers whenever possible

·         Label and lock all storage areas, cupboards, drawers, storage cabinets, refrigerators, etc.

·         Locking will prevent accidental contact with chemicals or interference with equipment.

·          The fume chamber should be labelled. It should be kept in good condition to minimize unexpected gas leakages or emissions.

·         Gas cylinders should be labelled, stored properly, and supported. Moreover, they should be in good working conditions all the time.

·         Each laboratory should be equipped with adequate first aid kits.

·         Equipment for monitoring contamination should be installed to give alerts of any possible dangers.

·         Always keep tables, seats, fume hoods, floors and desks clear of unnecessary material.

·          All equipment should be inspected before use. In addition, they should be checked regularly to ensure they are safe for use.

·         The laboratory must have wide emergency exits and wide windows. Wide exits facilitate easy evacuation in case of emergency. Wide windows allow enough air to enter and circulate in the laboratory. (Note: Maintain at least two clear passages to laboratory exits).

NOTE: All the above rules and safety measures should be followed and observed as possible.

FIRST AID

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

Whenever an accident occurs, something must be done immediately to help and save life of the victim. You must always be ready to give a hand to a victim whenever an accident occurs close to you. To take aid effectively and successfully, one must possess some knowledge on how to assist different (a person who is injured) victims. When you do not know how to aid a certain victim, you can ask someone to assist instead. Do not engage yourself in assisting if you actually do not know where to start. You may find yourself worsening the situation of the victim unknowingly.

IMPORTANCE’S OF FIRST AID TO A VICTIMS

The following are the importance of first aid to a victim.

·         relieve pain and bring hope to the victim.

·         prevent permanent disability

·         prevent the victim’s condition from getting worse

·         reduce the possibility of death.

·         shorten recovery time

what cause accidents in chemistry laboratory?

Answers

Some possible causes of accidents in the laboratory include:

Failure to follow the correct experimental procedures for example, pouring water into an acid instead of pouring an acid into water as the rule is.

Neglecting some laboratories rules such as ignoring to wear protective gears, tasting the chemicals, eating or drinking while in the laboratory, etc.

Failure to adhere to proper conduct in the laboratory like running unnecessarily and conducting experiments without your teacher's or technician's permission and guidance.

Improper use or handling of laboratory equipment and apparatus when conducting experiments, which could lead to breakage and in turn cause cuts, bruises, grazes, etc.

Improper disposal of chemical wastes may result in explosions, burns or even fires.

The leaking of gases from taps or cylinders may cause fires or even explosions.

Use of wrong reagents due to incorrect labeling of chemicals or use of reagents or chemicals that have expired may cause burns, poisoning or damage to apparatus or equipment.

Inadequate prior information or knowledge on procedures and hazards associated with certain practical activities or reactants may result in burns, poisoning or explosions.

Loose or improperly plugged electrical appliances may cause electric shock, especially when touched with wet hands and during fixing of sockets

Accidental spillage of chemicals on body parts such as hands, face, eyes, etc., could lead to burns and damage.

Poor ventilation in the laboratory may cause suffocation (due to inadequate oxygen supply) and poisoning (by inhaling poisonous gases produced when experimenting).

A FIRST AID KIT

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

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

First aid kit with components and their uses or function.

Below shows each type of chemical found in a First Aid Kit and its function: -

Tool/chemical/item Function

·         First aid manual Contains: guidelines on how to use the items in the first aid kit

·         Sterile gloves: Worn on hands when attending bleeding cuts or wounds to avoid infecting wounds and to prevent direct contact with the victim’s body fluids

·         Sterile dressing: Stops bleeding

·         Antiseptic agent, Cleaning and disinfection of wounds, cuts, bruises, grazes or blisters

·         Washing hands, wounds and equipment

·         Antibiotic ointment: Prevents infection on cuts and bruises in or near the eye

·         Burn ointment:   Applied on burns to prevent infection

·         Petroleum jelly:  Soothing broken skin

·         Plaster or adhesive bandage: Covering small wounds or cuts

·         Sterile gauze:     Covering wounds to protect them from dirt or germs

·         Eye wash solution: Flushing the eyes or as a general decontaminant

·         Thermometer:      Recording body temperature

·         Antibiotic novelettes or cotton wool:  Cleaning and drying cuts and wounds

·         Iodine tincture:           Dressing fresh cuts and bruises

·         Pain relieving drugs:  such as aspirin, paracetamol, Panadol, etc. Relieving mild pains

·         Liniment: Reducing muscle pain

·         Mild antibiotics: Treating mild bacterial infections on the skin, ear, nose and mouth

·         Gentian violet solution:  Applied on minor wounds and treatment of serious heat wounds

·         Hydrogen peroxide: solution Cleaning wounds

·         Methylated spirit (70% alcohol): Cleaning cuts and bruises

·         Bandages: Dressing wounds and cuts, and immobilizing injured limbs

·         Scissors or razor blade: Cutting dressing materials

·         Dental kit: Treatment of broken teeth, loss of crown or filling

·         Safety pins (small and big): Splinter removal and securing triangular bandage slings

·         Tweezers: Splinter or stinger removal

·         Resealable oven bag Container: for contaminated articles

·         Moleskin: Applied to blisters or hot spots

·         Triangular bandage: Used as a sling, towel or tourniquet

·         Boiled, clean water: Washing hands and drinking

·         Nasal spray decongestant: Nasal congestion from colds or allergies

·         Torch: Source of light

·         Whistle: Blown to call for help

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

First aid procedures:

Bleeding

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

(a) Internal bleeding

Signs and symptoms of internal bleeding include the following:

Bruised, swollen, tender or rigid abdomen

Bruises on chest, neck, legs or signs of fractured ribs

Vomiting or coughing up blood.

Abdominal pulse and difficulty breathing

Cool, moist skin

Fractures

Procedure

First aid in the field for internal bleeding is limited. If the injury appears to be a simple bruise, apply cold packs to slow down the bleeding, relieve pain and reduce swelling.

If you suspect more severe internal bleeding, carefully monitor the patient. Be prepared to administer CPR if required (and you are trained to do so).

Seek medical advice immediately if the situation seems to be worse.

(b) Severe bleeding

Procedure

Severe bleeding with blood oozing out rapidly must be stopped at once. This can be done by applying direct pressure to the wound. Use a dressing if available. If it is not available, use a rag, towel, piece of clothing or your fingers alone. If the wound is large, press the edges of the wound together but firmly. However, this should be done only if there is no fracture.

Lay the victim down in a comfortable position.

If the wound is on a limb, and provided it is not fractured, raise the wound above the level of the heart. Then continue to apply direct pressure. This should be done only if bleeding continues and if it does not cause pain.

If bleeding still cannot be controlled, the next step is to apply pressure at a pressure point. For wounds of the arms or hands, pressure points are located on the inside of the wrist (radial artery-where a pulse is checked) or on the inside of the upper arm (brachial artery). For wounds of the legs, the pressure point is at the crease in the groin (femoral artery).

When bleeding stops, clean the wound carefully and thoroughly with a suitable disinfectant. Do not remove any objects stuck in the wound, as this would lead to more bleeding.

Place sterile gauze on the wound and press it down firmly. Cover it with a soft material and hold it in position using a firm bandage. After the bandage is in place, it is important to check the pulse to make sure blood circulation is not interrupted. A slow pulse rate, or bluish fingertips or toes signal a bandage may be hindering blood circulation.

Visit medical help immediately.

(c) Light bleeding

Procedure

Place the victim in a comfortable resting position.

Elevate the injured part while applying pressure. This should be done only if the wound is on a limb and you do not suspect a fracture.

Gently and thoroughly clean the wound using water and antiseptic or common salt solution.

Cover the wound with sterile gauze or clean dressing dipped in iodine solution.

Dress and bandage the wound

Take the victim to hospital if bleeding still continues.

(d) Nose bleeding

Causes of nose bleeding

It is. occurs near the tip of the nose.

 The bleeding may be a result of the following;

high blood pressure, rheumatic fever, or injury. Low atmospheric pressure Nose bleeding is also likely to occur at high altitude because of low atmospheric pressure or extreme coldness.

nose-bleeding victim

Procedure:

Let the victim sit calmly: This makes the heartbeat to slow down and hence reduce bleeding.

Loosen clothing around the neck and chest.

Let the victim sit upright and lean the head forward slightly. By remaining upright, the victim reduces the blood pressure in the veins of his or her nose. This discourages further bleeding. Leaning forward will help the victim avoid swallowing blood, which can irritate his or her stomach.

Have the victim pinch his or her nose, to keep nostrils shut, using thumb and index finger. Ask the victim to breathe through the mouth. Let him or her continue pinching for a few minutes.

Apply cold, wet compression over the nose, face and at the back of the victim’s neck.

When bleeding stops, gently clean the nostrils.

If bleeding does not stop after 20 or more   minutes, take the victim to the hospital immediately.

prevention of re-bleeding after bleeding has stopped

 the victim should not to pick or blow the nose and not to bend down until several hours after bleeding.

Let the victim keep his/her head higher than the level of his/her heart.

If re-bleeding occurs:

Ask the victim to blow out forcefully to clear the nose of blood clots. Spray both sides of the nose with decongestant nasal spray.

Pinch the nose as described above and seek medical help.

Suffocation

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

Causes of suffocation 

Suffocation can be caused by 

drowning., electric shock.

 gas or smoke poisoning.

choking.

asthma.

severe infections of the throat or other causes.

Procedure

Remove the cause of suffocation or remove the victim from the cause of suffocation. Loosen tight clothing around the neck.

Make sure the victim’s airway is open for air to reach the lungs. This can be achieved by laying the victim on his or her back. Then, with one hand on the victim’s forehead and the other on the chin, tilt the head backwards, to open the airway. Tilt the head until the chin points straight upwards. If the airway is blocked by fluid or solid, remove it.

Administer cardiopulmonary resuscitation (CPR). This involves blowing air into the victim’s mouth (mouth-to-mouth breathing). 

How to apply CPR do this, pinch the nose and close up the mouth. Take a deep breath and then blow hard into the victim’s mouth. Watch the rise in chest and repeat the procedure until the victim’s breathing is restored. In case the person does not respond, go for chest compressions over.

Compressions can be done by placing the palm of one hand in the space between the nipples and the other hand over it and pushing the chest by using your upper body weight. Care should be taken to prevent chest injury or fracture. Two compressions can be given every second or hundred per minute. After thirty compressions, go for mouth breathing again. Repeat the procedure until natural breathing is restored.  Take the casualty to the hospital immediately .Example. diagram.

Figure03.

Chokin

Choking is the which occurs when food or a foreign object blocks the upper part of the windpipe. This interferes with normal breathing.

signs of choking The signs of this problem include difficulty in breathing and speaking. Have you ever been with a person who is chocking? Did you know what to do?

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

Procedure

Ask the victim to cough up the object.

If the object remains stuck, give firm but gentle taps between the shoulder plates.

If the object is still stuck, apply quick abdominal thrusts i.e. Heimlich manoeuvre as follows:

Stand behind the victim and make him or her lean forward slightly.

Put your arms around the person, placing your fist just below the breastbone. Grasp your fist with the other hand near the top of the victim’s stomach.

Press your fist onto the victim’s abdomen. Give a series of quick, sharp upward and inward thrusts to dislodge the object.

Thrusting to dislodge the object

Electric shock

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

Procedure

Switch off the main switch immediately if possible.

If not possible to put off the switch, detach the casualty from the source of electricity using a non-conducting object such as a dry wooden stick, cardboard, plastic or rope.

Loosen any tight clothing, necklaces, bangles, etc.

If the person is unconscious, apply mouth-to-mouth respiration (CPR) immediately.

Treat for shock, burns, bruises or other injuries the victim may have sustained. Lay the victim down, and if possible, position the head slightly lower than the trunk, with the legs elevated (shock position).

Take the person to the hospital immediately.

Caution

Do not touch the person with your bare hands if he or she is still in contact with the electric current.

Do not get near high-voltage electricity until power is turned off. Instead, call for help immediately.

Do not move a person with an electrical injury unless the person is in immediate danger.

Bruises

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

Procedure

Wash the bruised part of the body.

Apply a cold compress, such as a cloth dipped in cold water or ice wrapped in a cloth, to the injury. This helps reduce pain, swelling, and speeds up recovery.

If the bruise is on a limb such as arm or leg and it covers a large area, keep the limb elevated as much as possible for the past 24 hours.

Vomiting;

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

Possible causes of vomiting

Allergic reactions

Diseases e.g. malaria

Physiological condition e.g. pregnancy

Drinking contaminated water.

Inhaling poisonous fumes

Over-eating.

Food poisoning

Unpleasant smell or taste

Procedure

Give the victim an oral rehydration drink or oral rehydration salt solution. You may also provide a lot of any clear fluids.

Allow the person to have a complete rest.

Take the victim to hospital if:

Vomiting continues persistently.

The victim vomits blood.

The victim experiences high fever.

The victim is very dehydrated. This will be observed when the mouth and skin become very dry.

Fainting

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

How to cure fainting 

Procedure

Loosen or remove any tight clothing from the victim.

Make the victim lie down on his or her back.

Raise the legs of the victim (shock position) above the level of his or her head. This will increase the flow of blood to the brain.

Make sure the victim is exposed to plentiful supply of fresh air.

In case there is no improvement in a few minutes take the victim to the hospital

Muscle cramps

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

Signs and symptoms

Twitching of the muscle

A sharp, sudden and painful spasm, or tightening of a muscle (especially common in the legs).

Muscle hardness

Persistent cramping pains in the lower abdominal muscles.

Causes

Imbalance in certain minerals, body fluids, hormones, and chemicals that allow stretching and contracting of our muscles.

Malfunctioning in the nervous system.

Excessive physical activity and hormonal imbalances cause us to sweat. This brings about the loss of many essential minerals, such as potassium and calcium, which our body muscles need.

Procedure

Lay the victim down

Gently massage and stretch out the cramped muscle(s).

Apply some anti-cramp ointment to the affected area

If the problem persists, seek medical help immediately.

Stretching and massaging the muscles

Hiccups

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

Procedure

Give the affected person a polythene bag and encourage him/her to re-breath her own expelled air.

Ask the person to drink a glass of cold water quickly.

Tell the victim to hold his/her breath for as long as possible.

Tell the victim to pull on his/her tongue.

The victim may swallow finely crushed ice.

Chemistry laboratory apparatus

 Laboratory apparatus are those instruments which used for carrying out various experiments in the laboratory

Basic chemistry laboratory apparatus and their uses

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

apparatus for grinding e.g. mortar and pestle;

apparatus for storage e.g. reagent bottles and wash bottle;

apparatus for taking measurements e.g. thermometer, burette, pipette, measuring cylinder, measuring flask, beam balance, electronic balance, common balance, measuring syringe, beaker and stop watch;

apparatus for doing chemical reactions (or testing) e.g. beaker, test tube, dropper, flask, watch glass, gas jar and thistle funnel.

apparatus for safety e.g. goggles and hand gloves.

apparatus for holding things e.g. test-tube holder, retort stand and clamp, test-tube rack, tongs and tweezers;

apparatus for heating substances e.g. boiling tube, pipe clay triangle, crucible and lid, wire gauze, deflagrating (combustion) spoon, Bunsen burner, spirit lamp, tripod stand, evaporating dish, wire gauze and stove;

apparatus for filtering e.g. filter funnel, filter paper and cotton wool;

apparatus for scooping e.g. spatula.

The Apparatus Used in a Chemistry Laboratory

Categorize chemistry laboratory apparatus according to their uses

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

Table summarizes some common laboratory apparatus and their uses.

Composition and uses of some chemistry laboratory apparatus

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

Common Chemistry Laboratory Apparatus

Use common chemistry laboratory apparatus

Common laboratory apparatus.

                                   Figure:04

Activity 

Someone may guide you especially your teacher how to measure the volume of liquids using the other apparatuses.

Aim: To measure volume of liquids using different apparatus

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

Procedure

Pour some water into a graduated measuring cylinder with a capacity of 100 cm3. Add the water, one drop at time, up to a 25-cm3 mark.

While adding water, position yourself at eye-level with the mark on the cylinder. This will enable you to obtain the most accurate measurement. To simplify the work of reading the level of the water, you may use coloured water.

Select a volumetric flask measuring 50 cm3. Pour the water into the flask until it reaches the mark on the flask’s neck.

Position yourself at eye-level with the mark. You will obtain the most accurate reading when the mark appears straight rather than elliptical. To obtain this, put a flask on a flat table.

Add water one drop at a time. Do so until the bottom of the curved surface of the water exactly matches the mark on the flask.

Activity 

Aim: To measure the masses of solid objects

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

Procedure

Put an empty watch glass on the weighing balance. Note down its mass. Record this as mass M1.

Place the various items you have on the watch glass, one item at a time. Note down the mass. Record this as M2.

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

For example
i.Warning signs

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

Note When performing experiments in the laboratory it is important to read carefully and  know the safety signs on chemical containers. This will reduce the chances of causing accidents in the laboratory.

The Basic Chemical Warning Signs

Some chemical warning signs

Explain the concept of warning signs:-

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

                                                       
Toxic

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

                                                       Figure:06
Corrosive

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

                                                Figure:06, Corrosive

Flammable

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

                             Figure :07 ,Flammable.

Explosive

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

                                 Figure:08, Explosive.

Oxidizing agents

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

                               Figure08, Oxidizing agent

Harmful or irritant

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

                                               Figure09.

TOPIC 3: HEAT SOURCES AND FLAMES

Heat sources

In most cases chemical reactions require heat to proceed. therefore, it is important to have sources of heat in a laboratory for heating various reacting substances. Sources of heat in a chemistry laboratory may include Bunsen burner, candle, spirit burner, kerosene burner (stove), tin lamp (and charcoal burner.;

Different Heat Sources which can be Used in a Chemistry Laboratory:

The Bunsen burner is the best of all burners because it is convenient to handle. Another advantage of the Bunsen burner is that it produces a hot flame whose temperature is approximately 1000°C. The temperature can be adjusted easily to produce a non-luminous flame, which does not produce much soot.

Spirit burner

The spirit burner can also produce a soot-free flame. But the flame is not hot enough to effect (produce) some chemical reactions. Apart from that, the burner is filled with spirit, a substance that is highly flammable.

                                Spirit lamp figure

A candle

A candle can only be used where a chemical reaction does not require much heat. Its disadvantage is that it produces a lot of soot. The other burners, though not commonly used, are an electric heater and a gas burner.

The electric heater uses electricity. The gas burner uses a liquefied gas. The disadvantage of an electric burner is that it cannot be used in rural areas where there is no electricity.

                                   Candle figure. 10

A kerosene burner

A kerosene burner (stove),  if well-adjusted can produce a flame hot enough to heat many substances in the laboratory. It is fulled with kerosene, a fuel that is convenient to carry and store. This fuel does not catch fire easily as compared to spirit and it is affordable

It can conveniently be used by schools in the most remote areas where there is no electricity. If too much heating is required, wire gauze should be placed on top of the burner. This will enable reduce soot and increase the heating temperatures to about 1000°C or more.

              Kerosene Bunner Figure: 11

A charcoal burner

A charcoal burner can also be used in remove areas. In case the kerosene burner is not available, for one reason or another, a charcoal burner can be the best alternative.

The red-hot charcoal on the burner is almost soot-free. It can produce high temperature sufficient to carry out many reactions.

A tin lamp

A tin lamp (kibatari), though it produces a lot of soot, can also be used as a burner in a laboratory, especially in remote areas.

However, the heat it produces is not hot enough to initiate some reactions.

                            Figure10.9, Atin lamp

Bunsen bunner

The Functioning of a Bunsen Burner

Of all the burners we have discussed so far, a Bunsen burner is the mostly used. Therefore, we are going to discuss about the functioning of the Bunsen burner in more detail. As the name suggests, this burner was invented by a German scientist called Robert Bunsen, so it was named after his name as a Bunsen burner. The burner uses coal gas, which burns with a hot and non-luminous flame when the air holes are open. This is a kind of flame we normally use in the laboratory.

Base: Supports the burner. It makes the burner stable, due to its heavy weight, when placed on a bench.

Gas inlet: Lets the gas in from the gas supply.

Jet: Directs the gas to the barrel

Collar: Regulates the amount of air entering the burner. It has air holes that can be turned open or closed depending on the kind of flame, and hence amount of heating required.

Air holes: These small holes on the collar allow air to enter in the burner.

Barrel: This is a part of the burner where air (from outside), and gas (from gas supply) mix up and burn.

Figure11.Bunsen bunner

How we can   light a Bunsen burner

After knowing the different parts of the Bunsen burner, it is important that you also learn how to light it. This is because careless use of the burner may lead to accident or wastage of the gas. The following is a correct sequence of steps on how to light the Bunsen burner:

Connect the Bunsen burner by a rubber tube to the gas supply.

Close the air holes.

Turn the gas tap on to let in sufficient gas.

Quickly bring a flame at the top of the barrel. You may use a matchstick, a lighter or wooden splint as a source of flame.

Turn the collar to adjust the air holes until you get the type of flame you want. You may have the holes completely open.

Adjust the gas tap until the gas supply is enough to produce a non-luminous flame.

Note To put off the flame of the burner after you finish heating a substance, turn the gas tap off in order to cut off the gas supply to the burner. Disconnect the burner from the gas mains by removing the rubber tube connecting the two. Then close the air holes. Pay attention not to touch the hot collar with your fingers or else wait until it is cool enough. Take the Bunsen burner and keep it at the appropriate place

Types of flame

Flames are formed by burning gases or vapours. During burning, heat and light are given out. For any solid or liquid to burn with a flame, it must first turn into inflammable vapours (gaseous state).

Luminous and Non-Luminous Flames from Different Types of Flames

Produce luminous and non-luminous flames from different types of flames

A flame can be luminous or non-luminous. Flames of a candle and any oil are usually smoky and luminous. Flames of such kind are normally of little laboratory use. This is because they are not hot enough and would deposit soot on laboratory apparatus. Coal gas also burns with a smoky and luminous flame. With a Bunsen burner, one can produce two types of flames namely, the luminous and non-luminous flames.

Luminous flame

This is a type of flame produced when the air holes of a Bunsen burner are closed. When the air holes are closed very little air enters the barrel of the burner. In this case, the flame will be large, unsteady and bright

The flame will have four main zones each having a distinct colour.

Mchoro

Luminous flame

The inner dark zone - This is dark, cool and contains unburnt gas

Luminous yellow zone - The gas burns in this zone but because the air is not enough the burning is incomplete. This leads to formation of tiny carbon particles from the gas. When these particles are white-hot, they result in formation of light (the yellow colour we see). If a cold evaporating dish, porcelain crucible, or glass is placed in this zone, it will blacken due to deposition of carbon particles (soot) on it.

Outer zone - This is a non-luminous zone where the burning of the gas is complete due to presence of enough air. Because of the absence of carbon particles, this zone does not give out light. Consequently, the zone cannot be seen easily.

Blue zone – Due to rising convectional current, there is sufficient supply of air for complete burning at this zone.

Non-luminous flame

When air holes are fully opened, sufficient air enters the Bunsen burner barrel and mixes well with the coal gas. Hence, the burning of the gas is much quicker and complete. The flame is smaller and hotter.

Due to absence of white-hot carbon, no light appears. The flame is therefore non-luminous. The flame has three district zones each with a different colour.

Mchoro

Non–luminous flame

Cool inner zone – this is a zone of unburnt gas.

Green/blue zone - part of the gas burns in this zone because there is not enough air to burn all the gas completely. However, no carbon is formed. The hottest part of the flame is at the tip of this zone.

Outer purple zone – Burning of the gas in this zone is complete.

Major differences between luminous and non-luminous flames

Non luminous flame	Luminous flame
1. Formed when air holes are open are closed	Formed when air holes
2. Very noisy	Silent or calm
3. Comprises of three zones zones	Comprises of four
4. Forms no smoke or soot on apparatus	Forms a lot of smoke or soot on apparatus
5. Blue and almost invisible clearly visible	Bright yellow and
6. Very hot flame	Not a hot flame
7. Not bright	Very bright
8. Triangular flame	Wave-like frame

TOPIC FOUR 4: THE SCIENTIFIC PROCEDURES

THE SCIENTIFIC PROCEDURE

The Concept of Scientific Procedure

The scientific method (procedure) is a process that scientists use to ask questions and conduct investigations to find answers to these problems. It is a logical approach to problem solving by observing and collecting data, formulating hypotheses, testing hypotheses, and formulating theories that are supported by data. The scientific method provides a standardized way for scientists to conduct their work. However, many scientists work accor

Importance of scientific procedures

It gives a means by which one can get a solution to several questions about natural phenomena, e.g. why does water expand when it freezes?

It may lead to discoveries and innovations.

Provides background knowledge upon which future references may be made.

It makes our sense organs more effective in exploring our natural world. That is, we become more sensitive to environmental changes.

It makes us use the available resources more sustainable in solving everyday problems.

Assists us in predicting the future outcome based on the present condition.

Assists us in testing the validity or the possibility of an event, phenomenon or problem.

The main steps of the scientific procedure

Each Step of the Scientific Procedure

Observation (identification) or statement of the problem

The first step of the scientific procedure is to identify a researchable problem. A problem is an obstacle that makes it difficult to achieve a desired goal, objective or purpose. It refers to a situation, condition or issue that is unresolved. Observation refers to identification of a chemical phenomenon. This may include observing the colour, smell, texture of a substance, and so on. Observing involves the use of senses to obtain information. Observation is more than the bare fact of observing. It is determined by use of five senses namely, smell, touch, taste, vision and hearing. For example, to identify the colour of a substance you have to see it with your eyes. The same case applies to detection of the smell of a substance or gas produced by reacting substances in a laboratory. To be able to detect the smell of a gas you have to use your nose to smell it.

Observation helps a scientist to identify a problem. Observation may involve making measurements and collecting data. The data may be descriptive (qualitative) or numerical (quantitative) in nature. Numerical information such as the fact that a sample of sulphur powder measures 50g is quantitative. Non-numerical information, such as the fact that the colour of anhydrous copper (II) sulphate is white, is qualitative.

Once you identify a problem, it becomes easy to state it scientifically. For example, you can observe that when you put a given volume of water in a narrow container and expose it to open air, it takes much longer to evaporate and decrease in volume. However, when you put the same amount of water in a wide container, it takes a much shorter time to do so. This phenomenon can be investigated scientifically.

Hypothesis formulation

After identifying and stating the problem, you can formulate a testable hypothesis for that problem. A hypothesis is a statement. It is a prediction or proposed solution to a problem based on prior knowledge or known information about a chemical phenomenon. It is a logical guess about the outcome of the experiment. A hypothesis must be able to be tested. Therefore, a hypothesis can be described as a tentative explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation. It can be rejected, modified, or accepted only after conducting an experiment to prove or disprove it.

Let us take an example of water at the previous stage. It was observed that the water held in a wide container evaporated faster than that in a narrow container. Based on what we know about evaporation (prior knowledge) we can formulate a hypothesis pertaining to this phenomenon. It is well known that one of the factors affecting the rate of evaporation is the surface area. From this fact, we can formulate a testable hypothesis which states that “evaporation of water increases with increase in surface area of the container in which that water is placed”. This is just a statement. It can be proved wrong or correct by setting up and doing an experiment. Remember that this is just an example, though not very much related to chemistry. We can turn to another relevant example as well.

Now, let us look at an example of anhydrous copper (II) sulphate. The anhydrous salt is in powder form. When you expose this salt to open air, it changes its colour and shape, from its original white powder to blue crystals. Why does this happen? From our knowledge of the properties of this salt (prior knowledge or information gathered) when it is placed in open air, it absorbs water vapour from the air. It is this water vapour which it absorbs that turns it blue. We can go as far as formulating a hypothesis, which states that "When white anhydrous copper (II) sulphate powder is exposed to open air, it absorbs water vapour from the air and turns into blue crystals". We still have a doubt about this hypothesis. How do we know that the liquid absorbed by the salt is really water? To accept or reject this hypothesis, we must conduct an experiment.

Experimentation

After making a hypothesis, the next step is to plan and conduct an experiment. Planning an experiment involves writing down steps for an experiment that will answer the question. It should be remembered that experimental plan should include short and clear steps. It should also include the materials and methods that will be used in the experiment. These may include safety gears such as goggles, gumboots, gloves, etc. It must also state all expected hazards to be accompanied with the reacting substances or chemical phenomena being experimented. This could either occur as a result of mishandling chemicals or apparatus, improper experimental procedure or even testing the products obtained from the experiment.

In the scientific method, an experiment is a set of observations (qualitative or quantitative) made in the context of solving a particular problem or question. An experiment is conducted in order to retain or falsify a hypothesis concerning a particular phenomenon. The experiment is a basis in the practical approach to acquiring deeper knowledge about the chemical world.

Experimenting involves carrying out a procedure under controlled conditions in order to make observations and collect data. To learn more about matter, chemists study systems. A system is a specific portion of matter in a given region or space that has been selected for study during an experiment or observation. When you observe a reaction in a test tube, the test tube and its contents form a system.

Your experiment tests whether your hypothesis is true or false. It is important for your experiment to be a fair test. You conduct a fair test by making sure that you change only one factor at a time while keeping all other conditions the same (constant). These factors are also called variables. They are the factors that affect the problem you want to investigate. They can change or be changed during the experiment. Such factors include temperature, volume, speed, light, concentration, light, etc.

Students conducting an experiment

There are three types of variables. These are:

Dependent variable: This is the factor that changes its value when the values of the other variables change. It is the value being measured.

Independent variable: This is the factor that is manipulated so as to obtain different values.

Controlled (or constant) variable: This is the factor that does not change, or is kept constant all the time. It does not affect the result of the experiment.

For example, you might be interested to carry out an experiment to determine the influence of the concentration of phosphorus fertilizer on maize growth. To get the best results, you grow maize in similar conditions of soil and atmospheric environment (controlled variable) but vary the quantity of fertilizer in each test (independent variable). Then you measure the height of maize plants (dependent valuable) after a certain interval of time as shown in figure below. The value of the height you will obtain will obviously depend on the amount (concentration) of the fertilizer applied. This is a typical fair test. However, most chemistry experiments do not involve fair tests.

Now, let us turn back to our experiment. In the example of determining whether the surface area increases the rate of evaporation or not, we can design an experiment to prove or disprove this phenomenon. This is conducted by filling a basin (with large surface area) and a bucket (with small surface area) with 10 litres of water each. Then the two containers are placed in open air for 3 days. Here, care must be taken to place both containers under similar environmental conditions. Containers must be of the same type, that is, both must be plastics, metals, etc. In addition, the water used must be obtained from the same source.

The effect of fertilizer on plant growth

The only variable to be kept constant is the volume of water, which is set to the volume of 10 litres. You should repeat your experiment several times to make sure that the first results were not just an accident.

Determination of the effect of surface area on the rate of evaporation of water

Observation and collection of data

Observation and recording of data must be done from the beginning to the end of the experiment. Data is the information gathered during the experiment. This can include descriptive (qualitative) and numerical (quantitative) data. Numerical data is that which can be measured, for example, 10 litres of water, 5g of copper, a five centimetre long ribbon of magnesium, etc. Qualitative data include information that cannot be measured, e.g. colour, shape or appearance, smell, feel, etc. Recording data is an important part of the scientific method because it helps scientists organize their ideas and observations. Charts, graphs, lists, diagrams, tables and even sketches are all the ways of recording data during experiments. Records appearing in the form of tables are easy to read, understand and interpret.

Continuing with our hypothetical experiment for determining the effect of surface area on the rate of evaporation, we expect that at the end of the experiment the volume of water in each container will have dropped to a certain extent.

We also expect that the volume of water lost from the basin will be bigger than that lost from the bucket. This means that more water will evaporate from the basin than from the bucket. Considering that scenario, we can then predict what the data can be like. Let us take this model as a real experiment and assume the kind of results that could be observed and collected during the experiment.

After 3 days of the experiment, water from each container was measured. The results obtained were summarized in the following table.

Source: hypothetical

Data collected from evaporation experiment after 3 days

Amount of water Type of container

Basin Bucket

Initial volume Final volume 10 litres 7.0 litres 10 litres 8.5 litres

Amount of water lost (evaporated off) 3.0 litres 1.5 litres

Data analysis and interpretation

Once your experiment is complete and after you have collected data, you analyse your data to see if your hypothesis is true or false. In table 4.1, we find that, at the end of the experiment, 3 litres of water had evaporated off from the basin as compared to 1.5 litres from the bucket. What does this data tell us? What is it trying to reveal? This means that from the basin (with large surface area) water evaporated faster than that from the bucket (with small surface area). The data reveals the fact that surface area plays a major role in evaporation of water and many other liquid substances.

However, you may sometimes get unexpected results. You may find that your hypothesis was false. In such a case, you will construct a new hypothesis and start the entire process of the scientific method over again. Even if you find that your hypothesis was true, you may want to test it again in a new way.

Conclusion

The last stage (at this level of study) of the scientific method is to make inferences and draw a conclusion. Scientists look at the information they gathered and observed. Then they make connections to draw a conclusion. These conclusions may be or may not be in agreement with their predictions. Scientists make incorrect predictions all the time. An important part of the scientific process is to understand why predictions were incorrect. Many scientists will repeat an experiment several times to see if they can replicate the results before concluding. This ensures that they have conducted the experiment the same way each time and make sure no introduced errors or outside factors affected the experiment's outcome.

Based on data in a hypothetical experiment above, we found that 3.0 litres of water evaporated from the basin (a container with wide mouth and hence a large surface area). At the same time, 1.5 litres of water evaporated from a bucket (a container with a narrow mouth and hence a small surface area). From this result, of course, we can conclude that evaporation of water increases with increase in surface area of the container in which that water is kept. Therefore, our hypothesis is proved true and correct. Remember always to base your conclusion on the collected and analysed data, though it may deviate, to some extent, from the reality for one reason or another.

NB: ADDITIONAL NOTES ON SCIENTIFIC PROCEDURE

In advanced study, the last step of the scientific method is to share what you have learned. Scientists share information so that others can use the findings to create different questions and conduct different experiments. Sharing information is an important part of working together. Professional scientists will publish their final reports in scientific journals, magazines, books, or even present their results at scientific conferences. For the purpose of study at this level, the last step is conclusion.

Even though we show the scientific procedure as a series of steps, keep in mind that new information or thinking might cause a scientist to back up and repeat steps at any point during the process. A process like the scientific method that involves such backing up and repeating is called an iterative process. Therefore, the scientific process is an iterative process.

Application of the scientific procedure

The scientific procedure is used in many areas and in different fields of study. It is especially applied by scientists and researchers to find solutions to various scientific problems. Below are some of the areas where the scientific procedure is applied:

In scientific research: Researchers normally apply the scientific method when conducting researches on diverse scientific problems or phenomena. A researchable problem whose solution is sought for without following the correct sequence of the steps of the scientific method is not likely to get resolved.

In a field study: A field study (or field work) is often conducted to find answers to problems or test hypotheses. It involves doing some practical work that applies the scientific methods.

When conducting experiments: An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the accuracy of a hypothesis. Experiments vary greatly in their goals and scale, but always rely on repeatable procedure and logical analysis of the results.

In project work: A project is a planned piece of work that involves careful study of a subject or problem over a period of time, so as to find information on the subject or problem.

The Scientific Procedure to Carry Out Investigations in Chemistry

Use the Scientific procedure to carry out investigations in chemistry

In this chapter, we have used two major examples to explain the concept of experimental procedure in detail. These are the rate of evaporation of water and exposure of anhydrous copper (II) sulphate powder to open air. For easy understanding and quick reference by students, the two examples are summarized below. Note that the test for the anhydrous copper (II) sulphate powder was not explained in full. However, the summary can give you a good picture on how to go about experimenting it.

·         The rate of evaporation of water

Steps

Problem/question: Does surface area affect the rate of evaporation of water?

Hypothesis: Evaporation of water increases with increases in surface area

Experimentation: A basin and a bucket are filled with 10 litres of water each. They are left exposed to open air, under similar conditions for a period of 3 days.

Observation and data collection: After 3 days, the remaining water in containers was measured carefully. The results were recorded in a table.

Data analysis and interpretation: It was found that 3 litres of water had evaporated from the basin and 1.5 litres from the bucket. From this data, it was discovered that much water (3 litres) had evaporated from a container with large surface area (basin) as compared to only 1.5 litres of water that had evaporated from a container with a small surface area (bucket).

Conclusion: Since a large amount of water evaporated from the basin as compared to that from the bucket, it is correct to conclude that surface area affects the rate of evaporation of water and that the larger the surface area the higher is the evaporation. Therefore, the hypothesis is proved to be true.

·         B. Exposure of anhydrous copper (II) sulphate powder to open air

Steps to be followed

       First step Problem/question: Why does anhydrous copper (II) sulphate powder change into hydrated blue crystals when exposed to open air?

     Second step Hypothesis: When exposed to open air, the anhydrous copper (II) sulphate powder absorbs water vapour from the air and this water vapour turns it to blue crystals.

     Third step Experimentation: The anhydrous sulphate is exposed to open air to absorb sufficient water vapour. Then the hydrated sulphate is heated to drive out all the liquid in it.

      Fourth step Observation and data collection: The sample of hydrated blue crystals loses the liquid in it and turns to its original white powder. The vapour given off is carefully collected, cooled down to liquid, and then put in a beaker or test tube.

         Fifth step Data analysis and interpretation: The collected liquid is subjected to various water tests to justify whether it is water or just the other liquid substance. The liquid is identified as water.

        Lastly step Conclusion: The anhydrous copper (II) sulphate was exposed to air only. We also know that air contains water vapour. Because of this reason, it is correct to conclude that the water came from the water vapour contained in air. The water turned the white powder to blue crystals. Therefore, our hypothesis is true.

Activity one

Aim: To find out if chalk dissolves in water

Materials: Beakers, tap water, pieces of chalk, mortar and pestle, sieve, crucible, stirring rod, source of heat, tripod stand, match box and sticks, tongs.

Procedure:

Note: Before you start, formulate a hypothesis for the experiment.

Take four pieces of blackboard chalk and break them into halves.

Put the broken pieces of chalk in a mortar and pestle.

Use the pestle to grind the chalk into a fine powder. To obtain the finest powder, sieve the resulting powder with a sieve.

Put the sieved chalk dust in a beaker.

Add water to the chalk dust in a beaker until it is half-full.

Stir the mixture vigorously for about 15 minutes.

Let the mixture settle overnight. Observe whether any dissolution has occurred.

 discussion the following question

What hypothesis did you formulate?

Could you see any particles of chalk after stirring?

Could you still see any particles after settling?

Is your hypothesis false or true?

Draw a conclusion based on your findings.

READ TOPIC 5: Matter

5. Matter

Matter is anything that occupies space and has mass. Matter contains particles that are atoms, molecules. Matter exists in three states 

Solid

Liquid

Gas

 Examples;

Solid- Brick, block of ice, wall.

Liquid- Water, soda, tea.

Gas- Oxygen, nitrogen, carbon dioxide.

Element: Is a single pure substance that cannot be broken down into simpler substances by any chemical means.

An element contains one type of atom.

Atom: Is the smallest particle of an element which can participate in a chemical reaction.

The atom of an element has all the properties of that element.

The building block of matter is atom.

Atom->Element->Matter

Molecule- Occurs when two or more nonmetal atoms come together.

Examples:

Solid- Aluminum, copper, uranium.

Liquid- Mercury, bromine.

Gas- Hydrogen, nitrogen, oxygen.

 Elements can be metals or nonmetals.

Metals- Lead, copper, gold, zinc.

Nonmetals- Fluorine, chlorine, neon, oxygen.

Properties of metals:

Lustrous- Shine when polished.

Ductile- Can be drawn to a wire.

Malleable- Can be hammered on a sheet.

High boiling and melting.

Good conductors of heat and electricity.

Properties

Properties of solid state

Particles are close together.

Strong force of attracts