1 prepared by mrs yvonne loi the chinese high school

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Prepared byMrs Yvonne LoiThe Chinese High School

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Objectives• To discuss what the science process skills

and attitudes important to the learning of science are

• To state the laboratory safety rules and recognise the various hazard symbols

• To state the names and functions of some common laboratory apparatus (listed in workbook)

• To draw, in proportion, sectional diagrams of the apparatus

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Objectives• To dismantle the Bunsen burner and

explain how the various parts contribute to its working

• To know the procedure of lighting a Bunsen burner and able to light it correctly and with confidence when doing practical work

• To obtain either a luminous or non-luminous flame by adjusting the size of the air holes

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Objectives• To draw the diagram of a non-luminous

flame and label the various parts, i.e. dark zone of unburnt gas, blue zone of partial combustion, almost colourless zone of complete combustion and hottest part of the flame

• To explain the causes of the luminous and non-luminous appearance of the flame

• To state which flame is more suitable for heating and explain why

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Objectives• To carry out appropriate action during a

strike back

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Do you know what science is all about?The influence of science is all around us.

For example, a homemaker needs to know science to cook well-balanced and nutritious meals for his or her family.

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Many devices that we used, such as the telephone, cassette player and fluorescent lamp, are based on scientific discoveries.

Fight against diseases such as AIDShas been largely carried out byscientific research.

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Scientists are also making new discoveries to solve global problems such as air and water pollution. From such findings, they are able to warn us about new hazards to our health so that certain precautions can be taken.

Hazy weather

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Science As An Inquiry

Science is the systematicstudy of nature and howit affects us and theenvironment.

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Branches of Science:Biology - The study of living things.Chemistry - The study of substances and

how they interact.Physics - The study of matter, energy and

natural forces.Astronomy - The study of the sun, the moon,

the stars, planets and otherheavenly bodies.

Geology - The study of structures of earth.

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In the past, science was only described as a body of knowledge. Later definitions of science included the adoption of certain methods or skills to discover and apply scientific knowledge.

Today, the study and practice of science involve three major elements- attitudes- processes or methods- products

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Attitudes- Science encourages man to develop

positive attitudes.

The attitudes important to the learning of science are

Curiosity Perseverance

13Cooperation with others Tolerance

Positive approach to failure Open-mindedness

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Impartiality Healthy scepticism

Integrity Refusal to believe superstitions

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Processes or methods- Science process skills are used to develop

new processes or methods ofinvestigating and understanding science.

Science process skills refer to the different types of skills including thinking and reasoning skills, which are needed for scientific investigation. They are broadly divided into basic process skills and integrated process skills.

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To transmit and receive information presented in various forms - verbal,

written, tabulated, graphical or pictorial.

To group objects or events according to common

properties.

To use our senses to obtain information

about objects, events and changes.

The basic process skills are

Observe?

Communicate?

Classify?

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To approximate.

To find out the physical properties (e.g. length,

area and mass) of matter accurately with the help of

measuring instruments.

To draw conclusions from observations.

To make an educated guess of how things may

turn out based on previous experience or knowledge.

Infer? Measure?

Predict? Estimate?

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Integrated process skills require pupils to think at a higher level and to consider more than one thought at a time. They combine several of the basic process skills to form better ways of solving problems.

Scientists have to carry out experiments to test the hypotheses or to prove proposed concepts. In carrying out the experiments, several integrated process skills are required.

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The integrated process skills are

- Observing carefully and measuringaccuratelyThis skill involves using our five senses,sight, smell, hearing, taste and touch, togather information or make accuratemeasurements abouta topic under study.

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- Communicating effectivelyThis skill involves recording observationsor measurements in appropriate forms suchas tables, charts, graphs, labelled drawings,formulae and other forms ofcommunication for easy reference.

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- Making inference and developing ahypothesisAn inference is a statement one arrives atafter much reasoning based onobservations or measurements. The makingof an inference involves thinking skills anddiscussion with others to come up with thebest possible explanation for theobservations or measurements.

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For an inference, scientists usually comeup with a hypothesis which is a suggestedexplanation that can be tested throughexperiments.

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- Planning or designing experiments totest the hypothesisThis skill involves deciding what apparatusto use, how to put them together, whatobservations to make or measurements totake and how to do a fair test on thevalidity of the hypothesis.

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Science process skills will help you to expand your scope of learning in science as well as in other subjects through experience.

You begin with simple ideas which are combined to form new and complex ideas.

All your ideas are valuable because they help you to become a better decision maker, consumer, problem solver, citizen and member of our global society.

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Products- The information and ideas of science that

have been recorded as scientificknowledge are called products.

Most scientists build on what other scientists have discovered. This practice saves a lot of time and energy. As new discoveries are made, they are added to the scientific knowledge base. Thus science has changed over time and is subjected to further changes.

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The understanding of the three major elements of learning science is important to anyone who studies and practises science.

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Our innate experience often makes us curious (attitudes) about phenomena occurring in nature.

This curiosity about nature in turn motivates us to develop new ways of processing ideas or solving problems (processes or methods).

These lead to the construction of new scientific knowledge (products).

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Successful learning in science and other subjects is the result of carrying out continuous investigations relating to the subjects.

This will enrich a person’s experience.

A learning cycle is thus formed and continues to repeat itself as learning is a lifelong process that never stops.

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The Scientific Method

Different scientists may be carrying out different scientific investigations but they all share the common methods of investigation.

The scientific method is the most common method used by scientists in their investigations.

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The Scientific Method - Investigative

The steps in the Scientific Method- Observation- Hypothesis- Experiment- Conclusion

To actually do a science experiment, many more steps are needed. The following more accurately reflects the course of an actual experimental investigation.

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- Initial observation.- You notice something, and wonder why it happens.- You see something and wonder what causes it.- You want to know how and why something works.- You ask questions about what you have observed.

(Write down what you have observed.)

Example:

Cooking instructions tell you to add salt to water before boiling it.

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- Information gathering.- Find out about what you want to investigate.- Read books, magazines or ask professionals who might

know in order to learn about the effect or area of study.(Keep track of where you got your information.)

Example:

Cooking instructions tell you to add salt to water before boiling it.

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- Title the project.- Choose a title that describes the effect or thing you are

investigating.- The title should be short and summarize what the

investigation will deal with.

Example:

The Effect of Salt on the Boiling Point of Water.

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- State the purpose of the project.- What do you want to find out?

Example:

To find out how salt affects the boiling point of water.

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- Identify variables.- Based on your gathered information, make an educated

guess about what types of things affect the system youare working with.(Identifying variables is necessary before you can makea hypothesis.)

Example:

Variables - Amount of salt

Constant - Amount of distilled water- The container to use- The place to perform the experiment- etc.

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- Make HYPOTHESIS.- When you think you know what variables may be

involved, think about ways to change one at a time.- If you change more than one at a time, you will not know

what variable is causing your observation.- Sometimes variables are linked and work together to

cause something.- At first, try to choose variables that you think act

independently of each other.- At this point, you are ready to translate your questions

into hypothesis.(A hypothesis is a question which has been rewordedinto a form that can be tested by an experiment.)

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- Make a list of your answers to the questions you have.- This can be a list of statements describing how or why

you think the observed things work.- These questions must be framed in terms of the variables

you have identified.- There is usually one hypothesis for each question you

have.- You must do at least one experiment to test each

hypothesis.(This is a very important step.)

Example:

Adding salt to boiling water will cause the water to boil at a higher temperature.

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- Design experiments to test your hypothesis.- Design an experiment to test each hypothesis.- Make a step-by-step list of what you will do to answer

your questions.(This list is called an experimental procedure.)

- For an experiment to give answers you can trust, it musthave a “control.”(A control is an additional experimental trial or run. Itis a separate experiment, done exactly like the others.The only difference is that no experimental variablesare changed.)

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(A control is a neutral "reference point" forcomparison that allows you to see what changing avariable does by comparing it to not changinganything.)(Dependable controls are sometimes very hard todevelop. They can be the hardest part of a project.)

(Without a control you cannot be sure that changingthe variable causes your observations.)(A series of experiments that includes a control is calleda "controlled experiment.”)

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- Experiments are often done many times to guarantee thatwhat you observe is reproducible, or to obtain an averageresult.(Reproducibility is a crucial requirement. Without ityou cannot trust your results. Reproducible experimentsreduce the chance that you have made an experimentalerror, or observed a random effect during oneparticular experimental run.)

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- Boil 200 cm3 of distilled water on a stove.

- Measure the temperature of the boiling water.Record the highest temperature reading. This isthe control to compare with.

- Measure salt using a teaspoon. Level thespoonful.

- Add the measured salt to the boiling water andstir.

- Measure the temperature of the boiling waterwith the salt in it. Record the highesttemperature reading. REPEAT.

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Guidelines for experimental procedures.- Select only one thing to change in each experiment.

(Things that can be changed are called variables.)- Change something that will help you test your hypothesis.- The procedure must tell how you will change this one thing.- The procedure must explain how you will measure the

amount of change.- Each type of experiment needs a "control" for comparison so

that you can see what the change actually did.

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- Obtain materials and equipment.- Make a list of the things you need to do the experiments,

and prepare them.

- Salt- Distilled Water - Beaker - Teaspoon - Thermometer - Stirrer

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- Do the experiment and record data.- Experiments are often done in series.- A series of experiments can be done by changing one

variable a different amount each time.- A series of experiments is made up of separate

experimental “runs.”- During each run you make a measurement of how much

the variable affected the system under study.- For each run, a different amount of change in the variable

is used.

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- This produces a different amount of response in thesystem. You measure this response, or record data, in atable for this purpose. This is considered "raw data" sinceit has not been processed or interpreted yet. When rawdata gets processed mathematically, for example, itbecomes results.

- As you do experiments, record all numericalmeasurements made. Data can be amounts of chemicalsused, how long something is, the time something took,etc.(If you are not making any measurements, youprobably are not doing an experimental scienceproject.)

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Data Obtained: 2/25/95

Amount of boiling water 2 Cups Temperature of boiling water (Control) 100.0°C

Amount of salt added to boiling water: Run 1 1 TblTemperature of boiling water after adding salt: Run 1 101.0°C

Additional amount of salt added to boiling water: Run 2 1 TblTemperature of boiling water after adding salt: Run 2 103.0°C

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- Record your observations.- Observations can be written descriptions of what you

noticed during an experiment, or problems encountered.(Keep careful notes of everything you do, andeverything that happens.)

- Observations are valuable when drawing conclusions,and useful for locating experimental errors.

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- When the salt was added to boiling water itbubbled up more, and then stopped boiling.

- Shortly afterwards, it boiled again.

- If the thermometer extends beyond the outside ofthe beaker it reads a higher temperature.

- Heat from the Bunsen burner makes thethermometer read higher.

- Keep the thermometer over the beaker whenmaking temperature measurements.

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- Perform calculations.- Perform any calculations needed to turn raw data

recorded during experiments into numbers you will needto make tables, graphs or draw conclusions.

Total amount of salt added for Run #1:0 + 1 = 1 Teaspoon

Total amount of salt added for Run #2:1 + 1 = 2 Teaspoons

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- Summarize results.- Summarize what happened. This could be in the form of

a table of processed numerical data or graphs. It couldalso be a written statement of what occurred during theexperiments.

- It is from calculations using recorded data that tablesand graphs are made.

- Studying tables and graphs, we can see trends that tellus how different variables cause our observations.

- Based on these trends, we can draw conclusions aboutthe system under study.

- These conclusions help us confirm or deny our originalhypothesis.

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- Often, mathematical equations can be made from graphs.These equations allow us to predict how a change willaffect the system without the need to do additionalexperiments.

- Advanced levels of experimental science rely heavilyon graphical and mathematical analysis of data.

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Results.

Temperature of boiling water (Control) 100.0°C

Amount of table salt added to boiling water: Run #1 1 TblTemperature of boiling water after adding salt: Run #1 101.0°C

Total amount of table salt added to boiling water: Run #2 2 TblTemperature of boiling water after adding salt: Run #2 103.0°C

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- Draw conclusions.- Using the trends in your experimental data and your

experimental observations, try to answer your originalquestions.

- Is your hypothesis correct?- Now is the time to pull together what happened, and

assess the experiments you did.

Is the hypothesis correct?

Yes. Adding salt to water causes the water to boil at a higher temperature.

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Other Things You Can Mention in the Conclusion.- If your hypothesis is not correct, what could be the answer

to your question?- Summarize any difficulties or problems you had doing the

experiment.- Do you need to change the procedure and repeat your

experiment? - What would you do different next time? - List other things you learned.

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- Problems with doing the experiments.The temperature readings were hard to make.Gloves had to be worn to keep my hands fromgetting too hot.Had to be careful that the heat from the Bunsenburner was not hitting the thermometer.

- Other things learned.Be careful when adding salt to boiling water. Itmakes the water boil vigorously for a second ortwo.

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- Try to answer related questions.- What you have learned may allow you to answer other

questions.- Many questions are related.- Several new questions may have occurred to you while

doing experiments.- You may now be able to understand or verify things that

you discovered when gathering information for theproject.

- Questions lead to more questions, which lead toadditional hypothesis that can be tested.

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Why do you think cooking instructions tell you to add salt when boiling water?

When the water is hotter, you can cook foodfaster.

Salt also makes the food taste better.

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- What if my science project doesn't work?- No matter what happens, you will learn something.- Science is not only about getting “the answer.”- Even if your experiments don't answer your questions,

they will provide ideas that can be used to design otherexperiments.

- Knowing that something didn't work, is actually knowingquite a lot.

- Unsuccessful experiments are an important step infinding an answer.

- Scientists who study extremely complex problems canspend a lifetime and not find “the answer.”

- Even so, their results are valuable.- Eventually, someone will use their work to find the

answer. Are you that person?

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Example

Observation:

Record:Shadows are cast when objects block light.

Hypothesis:Light travels in a straight line.

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Experiment:

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Theory:The hypothesis that light travels in a straight line becomes a theory.

Law of science:After being tested a number of times and found to be true, the theory that light travels in a straight line finally becomes a law of science.

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Safety Rules in the Laboratory

Science experiments are usually performed in laboratories. Although performing experiments is fun, it can be dangerous if we are not careful. For our safety as well as the safety of others in the laboratory, we must follow laboratory safety rules.

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General safety rules- Do not enter the laboratory without the

teacher’s permission.- Open all doors and windows unless

otherwise instructed by your teacher.- Do not carry out any test or experiment

without the teacher’s permission.- Read the instructions first and understand

them before starting any experiment. If indoubt, always ask your teacher.

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- Handle all apparatus and chemicalscarefully and correctly. Always check thelabel on the container before using thesubstance it contains.

- Do not pour any unused chemicals back intoits container to avoid contamination.

- Do not taste any chemicals unless otherwiseinstructed by the teacher.

- Do not eat, drink or play in the laboratory.- Do not tamper with the electrical mains and other fittings in the laboratory.

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- Work tidily. Wash up all used apparatus anddispose of the waste correctly.

- Return the apparatus to their proper storageplaces after cleaning.

- Do not remove any apparatus or chemicalsfrom the laboratory.

- Wash your hands after all laboratory work.

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Safety rules when heating or mixing chemicals-- Wear goggles when mixing or heating chemicals.- Place flammable substances away from a

naked flames. - Point the mouth of a test tube or

boiling tube which is being heated awayfrom yourself or your friends.

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When accidents occurs- Report all accidents, injuries, breakage and spillage to your teacher immediately.- Should a chemical get into your mouth, spit

it out into a basin and rinse your mouth withplenty of water.

- If any chemical comes into contact withother parts of your body or clothing, washthoroughly with water and report to yourteacher.

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Susan

Shamala

Ali

Alice Meng Tat

Mike

Sleeping in the laboratory

Playing in the laboratory

Hair may catch fire if not tied up

The chemicals in the pipette may enter the mouth

Tampering with faulty electrical components

Pointing the mouth of the test tube which is being heated towards herself

Spillage of liquids on the bench

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Containers of dangerous chemicals are labelled with special symbols to warn others about the hazardous nature of the chemicals.

Symbol Type of Proper handlinghazardous substances

Flammable substancesExample:petrol, kerosene, alcohol

Keep flammable substances away from fire or heat.

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Explosive substancesExample:mixture of hydrogen and oxygen

Explosive substances usually explode when heated or lit. Use them according to the instructions given.

Corrosive substancesExample:strong acid and alkali

Avoid direct contact with the corrosive substances which can cause burns. Wash off any spilled acid or alkali on your skin or clothes with plenty of water.

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Poison or toxic substancesExample:mercury, cyanide, chlorine gas

Do not eat, drink or taste these poisonous substances. Use them according to the instructions given.

Irritating or stimulative substancesExample:chloroform, alcohol, bromine vapour

Avoid inhaling the vapour of stimulative substances. Use them in a fume chamber.

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!

This danger sign warns you to be careful.

When smelling unknown gases, fan a small part of the gas towards your nose.

Radioactive substancesExample:radioactive carbon, uranium, plutonium

Strictly adhere to all safety precautions when handling radioactive substances.

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Laboratory Equipment

There are many types of apparatus, especially glassware, in your school laboratory. Some common laboratory items are test tubes, beakers, conical flasks, measuring cylinders, test tube holders, gas jars, balances, tripods and retort stands.

You must know how to use these apparatus and draw each of them in outline only and in their correct proportions. (sectional diagram)

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For containing or heating small amount of substances

For containing or heating small amount of liquids

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For containing chemicals or collecting liquids

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For preparation of gases if the process requires heating

For containing chemicals when preparing gases if the process requires no heating

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For measuring a volume of liquid to an accuracy of 0.5 cm3

For measuring a volume of liquid to an accuracy of 0.1 cm3

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For measuring very accurately a specific volume of liquid, such as10 cm3, 25 cm3 and 50 cm3

For transferring liquids into a flask

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For separating an insoluble solid from a liquid with the help of apiece of filter funnel

For displaced liquid to flow out through its spout

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For collecting gases

For separating an experimentalset-up from the outside environment

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For evaporating a liquid from a solution

For heating solids directly over a flame

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For containing water when collecting gases

For supporting apparatus during heating

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For supporting apparatus during experiments

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To allow the distilled vapour to condense in order to collect the liquid

Liebig Condenser

For containing the liquid mixture which would distill the component liquid when heated

Distilling flask

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Bunsen burner

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Bunsen burner

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Bunsen burner

Barrel: to raise the flame to a suitable height for burning

Collar: to regulate the amount of air entering the burner through the air-holes

Gas tap: to control the flow of gas to the Bunsen burner

Air-holes: to allow air to enter the burner

Base: to support burner so that it will not topple

Jet: to enable the gas to rush out of the gas supply and to draw in air

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Lighting the Bunsen burner1. Close the air-holes.2. Strike a match and bring it to the top of the barrel.3. Turn on the gas tap with your free hand.

Types of flameLuminous flame - Produced when the gas does not

burn completely

Non-Luminous flame - Produced when the gas burnscompletely

Strike back - Produced when there is too much air

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Luminous flame- Occurs when the air-holes are closed,

insufficient air is allowed to mix with thegas therefore gas does not burn completely.

- Carbon particles are produced.- Orange in colour.- Appear flickering and unsteady.- Not very hot.

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dark zone of unburnt gas

blue zone of partial combustion

almost colourless zone of complete combustion

orange zone of incomplete combustion

Bunsen burner

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Non-Luminous flame- Occurs when the air-holes are opened,

allowing sufficient air into the burnertherefore gas is burn completely.

- Blue in colour.- Burns steadily.- Hotter than the luminous flame.- Hottest part of the flame is just above

the tip of the dark blue zone.

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dark zone of unburnt gas

blue zone of partial combustion

almost colourless zone of complete combustion

hottest part

Bunsen burner

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Strike Back- Occurs when there is too much air.- There is a large supply of air because the

air-holes are fully opened. - Instead of burning at the mouth of the

barrel, the gas burns atthe jet.

- When a Strike Backoccurs, turned offimmediately.

- Very hot.

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Heating a liquid in a beaker- The beaker is placed on a tripod stand.- A piece of wire gauze is placed between the beaker and the tripod stand.- The burner burner is then placed under the tripod stand and lighted.- The beaker is

removed fromthe flame whenthe liquid startsto boil.

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Heating a liquid in a test-tube- The test-tube must be held with a test-tube

holder.- Ensure that the mouth of the test-tube is

facing away from yourself or any otherperson.

- Slant the test-tubeat an angle ofabout 45O and heatit with a Bunsenflame.

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- Move the test-tube in and out of the flameoccasionally.

- The liquid to be heated should occupy nomore than one-third the height of the test-tube.

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Benefits and Abuses of Science and Technology

A lot of exciting discoveries and inventions have been made using science an technology. The way scientificdiscoveries andinventions are usedby people is calledtechnology.

Computer chips in silicon wafer

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Video conferencing, the Internet and cloning of animals are all products of technology.

Communication using satellites

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BenefitsTechnology has greatly benefited us as it has enabled us to grow more food, make our homes more comfortable, communicate faster over long distances,move from place toplace with ease andexplore outer space.

Vegetables grown using hydroponic methods

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The discovery of new medicines which can prevent or cure diseases, and the invention of

machines which can usedin medical treatmentenable us to live longerand healthier.

A patient with kidney failure receiving treatment

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Benefits of Science and Technology- Improve health- Prolong lifespan- Make lives more comfortable and

convenient- Enable people all over the world to

communicate- Reduce damage caused by natural disasters

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AbusesUnfortunately, scientific discoveries and technology have at times been misused by man.

For example, the inventionand use of deadly weaponsare harmful to us and theenvironment.

A nuclear explosion

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The abuse of science and technology has also resulted in different forms of pollution.

Factory chimney spewingpollutants into the air

We must therefore use science and technology with great care.

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Abuses of Science and Technology- Pollute the environment- Destroy lives- Deplete nature’s resources- Upset the balance in nature

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Limitations of Science

Although science has helped us in many ways, it must be noted that it has its limitations. Science cannot be used to find an answer to all our questions or to solve all our problems.

For example, we can use science to reduce the damages caused by natural disasters such as earthquakes and hurricanes but we cannot prevent them from happening.

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Science cannot- give life to non-living object.- forecast future events.- explain matters relating to religions.- help us return to the past or go to the future.

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References

Tho Lai Hong, Ho Peck Leng, Goh Ngoh Khang, (2001), Interactive Science 1, Pan Pacific Publications.

Chan Kim Fatt, Eric Y K Lam, Lam Peng Kwan, Loo Poh Lim, (2000), Science Adventure, Federal Publications.

Chuen Wee Hong, Lee Khee Boon, Hilda Tan, Ruth Chellappah, Koh Thiam Seng, Yap Kueh Chin, (2000), EPB.