CHEMISTRY NOTES FOR FORM ONE – ALL TOPICS

TOPIC 1 – INTRODUCTION TO CHEMISTRY


TOPIC 2 – LABORATORY TECHNIQUES AND SAFETY


TOPIC 3 – HEAT SOURCES AND FLAMES


TOPIC 4 – THE SCIENTIFIC PROCEDURE


TOPIC 5 – MATTER


TOPIC 6 – AIR COMBUSTION, RUSTING AND FIRE FIGHTING

IMPORTANCE OF CHEMISTRY IN OUR DAILY LIFE – PART 1 

1. Studying Chemistry Helps You Understand
How the World Works

Believe it or not, chemistry is part of
our everyday life. We encounter numerous principles of chemistry without even
realizing it. Many of the events that occur daily are results of chemical
reactions. Whenever you eat, drink, or even breathe air, certain chemical
reactions occur in your body. And without chemistry, we would not be able
to explain how these processes work. Therefore, studying chemistry is pretty
much essential for understanding how the world works. 

2. Chemistry can help you make informed
decisions. Will a product work as advertised or is it a
scam? If you understand how chemistry works you’ll be able to separate
reasonable expectations from pure fiction.

3. It can lead to new career opportunities

With the right qualifications and experience,
studying chemistry can lead to job opportunities in fields such as
biochemistry, forensic science, pharmaceuticals, and environmental sciences.
You may also be able to use your knowledge of chemistry in fields such as food
technology or materials science.

4. Chemistry helps explain everything

According to the American Chemical
Society, a non-profit organization, “Everything you hear, see, smell, taste,
and touch involves chemistry.” Chemistry helps explain things like why leaves
change color in the fall, why baking bread smells so delicious, and why some
people are allergic to things like peanuts. Everything that has matter breaks
down into chemical building blocks.

5. Improve the world

The importance of studying chemistry is
that it helps improve the world. As with all the sciences, chemistry has the
opportunity to make people’s lives easier. Developing new chemicals, materials
and medicines is an incredibly rewarding job. Chemists solve problems for
people and business alike.

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Explain the concept of Chemistry

Chemistry is a branch of science that deals with the study of nature, properties and composition 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, behaviour and nature of materials around us. This study enables us to make the best use of these materials to improve our welfare.

Materials Objects Made by Application of Chemistry

Mention 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 summarized in the table:

Some products made by application of chemistry

The importance of chemistry in life

Areas Where Chemistry is Applied

Mention areas where chemistry is applied

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)

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.

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, aluminium, tin, etc. Man has learned how to change harmful substances into useful products since the long ago.

Common salt may be made from twohazardous 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.

A woman washing clothes

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 fibres

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 behaviour 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 equipments 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.

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Heat sources

Most chemical reactions require heat to proceed. It is therefore 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 (kibatari) and charcoal burner. These are burners commonly used in most school laboratories.

Different Heat Sources which can be Used in a Chemistry Laboratory

Name 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

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

A kerosene burner

A kerosene burner (stove), also called jiko la mchina in Swahili, 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 burner (stove)

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.

Charcoal burner

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.

Tin lamp

The Functioning of a Bunsen Burner

Explain 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.

Functions of different parts of the Bunsen burner

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.

How to 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:

1. Connect the Bunsen burner by a rubber tube to the gas supply.
2. Close the air holes.
3. Turn the gas tap on to let in sufficient gas.
4. 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.
5. Turn the collar to adjust the air holes until you get the type of flame you want. You may have the holes completely open.
6. Adjust the gas tap until the gas supply is enough to produce a non-luminous flame.

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.

Luminous flame

1. Theinner dark zone – This is dark, cool and contains unburnt gas
2. 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.
3. 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.
4. 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.

Non–luminous flame

1. Cool inner zone – this is a zone of unburnt gas.
2. 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 tipof this zone.
3. Outer purple zone– Burning of the gas in this zone is complete.

Major differences between luminous and non-luminous flames

Investigation of different parts of a flame

We can easily find out whether or not the inside of a flame is cool. Two experiments can prove this:

1. (a) When a piece of cardboard is held horizontally over a non-luminous flame, we notice a burn mark as shown below:

When held vertically over the flame, the burn mark is as shown in above. Note that when performing this experiment, the cardboard should be withdrawn from the flame just before it catches fire. We find that the middle part of the cardboard does not get burned. This is the part in the zone containing unburnt gas.

Burn mark on cardboard when held horizontally

(b) If the above experiment is repeated using a wire gauze, we notice that the part in the middle will not become red hot except when the gauze is held in the flame for a long time.

Burn mark on cardboard when held vertically

We can prove the presence of unburnt gas in the Bunsen flame. This can be done by inserting a glass tube into the flame as shown in figure bellow

The unburnt gas can be shown to have risen up the tube by putting a light at the top of the tube. The flame will form. This indicates the escape of unburnt gas through the tube.

To indicate the presence of unburnt gas in a Bunsen burner flame

Uses of flames

Flames are used for different purposes. Some uses of the flames include the following:

• Production of heat for heating substances in thelaboratory: In this case, a non-luminous flame, which produces much heat, is used. However, for reactions that require little heat, a luminous flame, which is not very hot, can be used.
• Flame tests for elements: In chemical analysis of some elements, a flame test is one of the preliminary tests normally used to identify an element. When some elements are strongly heated, they produce characteristic flame colours that distinguish them from one another. A non-luminous flame is often used.
• Production of light: Flames produce light that can be used to light a dark room. Therefore, an experiment that involves heating can even be conducted in the dark. The same flame is used to give heat as well as light. Here, a luminous flame is used. Examples of heat sources, which produce flames that may be used for lighting, are hurricane lamp, tin lamp, spirit lamp and candle.
• Cooking: Since it gives a hot flame and produces no soot, a non-luminous flame can be used for cooking food. Gas cookers, gas stoves and kerosene stoves usually produce such flames.
• Welding: A non-luminous flame is suitable for welding because it is very hot. In most welding operations, an oxyacetylene gas, a mixture of oxygen and ethyne, is used. When burned, the gas produces a flame hot enough to cut or melt the metal.

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The Concept of Scientific Procedure

Explain 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 according to other methods as well.

The Importance of the Scientific Procedure

Explain the importance of the scientific procedure

Includes

1. The scientific procedure makes a researcher or an experimenter more systematic and organized when investigating or solving a problem.
2. 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?
3. It may lead to discoveries and innovations.
4. Provides background knowledge upon which future references may be made.
5. It makes our sense organs more effective in exploring our natural world. That is, we become more sensitive to environmental changes.
6. It makes us use the available resources more sustainably in solving everyday problems.
7. Assists us in predicting the future outcome based on the present condition.
8. 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

Describe 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

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.

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:

1. 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.
2. 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.
3. 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.
4. 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.

1. The rate of evaporation of water

Steps

1. Problem/question:Does surface area affect the rate of evaporation of water?
2. Hypothesis:Evaporation of water increases with increases in surface area
3. 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.
4. Observation and data collection:After 3 days, the remaining water in containers was measured carefully. The results were recorded in a table.
5. 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).
6. 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.
7. Exposure of anhydrous copper (II) sulphate powder to open air

Steps

1. Problem/question:Why does anhydrous copper (II) sulphate powder change into hydrated blue crystals when exposed to open air?
2. 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.
3. 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.
4. 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.
5. 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.
6. 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.