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Introduction to Science

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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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Attitudes- Science encourages man to develop

positive attitudes.

The attitudes important to the learning of science are

Curiosity Perseverance

Attitudes of a GOOD Scientist…

6Cooperation 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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How Scientist Work?

Refer to notes

The Scientific Method

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In the Science Laboratory…

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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.

Safety Rules in the Laboratory…

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- Do not enter the laboratory without theteacher’s permission.

General safety rules

- Open all doors and windows unlessotherwise instructed by your teacher .

- Do not carry out any test or experimentwithout the teacher’s permission.

- Read the instructions first and understandthem 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 into its 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 and dispose 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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- Wear goggles when mixing or heating chemicals.

Safety rules when heating or mixing chemicals

- Place flammable substances away from anaked flames.

- Point the mouth of a test tube orboiling tube which is being heated awayfrom yourself or your friends.

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- Report all accidents, injuries, breakage and spillage to your teacher immediately.

When accidents occurs

- Should a chemical get into your mouth, spitit 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 laboratoryHair 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.

Hazard Symbols…

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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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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)

Laboratory Equipments…

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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

For measuring a volume of liquid

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For measuring very accurately a specific volume of liquid, such as10.0 cm3, 25.0 cm3 and 50.0 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 paper

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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3-D of a Bunsen burner

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2-D of a Bunsen burner

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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

Parts of a Bunsen burner and their functions…

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To Light the Bunsen burner:1. The steps are: (i) Close the air-holes. (ii) Put the lighter above the barrel. (iii) Turn on the gas tap. (iv) Strike the lighter to ignite the gas.

(v) Open the air-hole until a non-luminous flame is obtained. Types of flameLuminous flame - Produced when the gas does not

burn completely (when air hole closed)

Non-Luminous flame - Produced when the gas burnscompletely (when air-

hole is partially opened)

Strike back - Produced when there is too much air (air-hole too big or air-hole opened too fast)

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- 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.

Luminous flame

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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

Luminous flame

Must learn how to draw and label the parts

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- Occurs when the air-holes are opened,allowing sufficient air into the burnertherefore gas is burn completely.

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

the tip of the dark blue zone.

Non-Luminous flame

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dark zone of unburnt gas

blue zone of partial combustion

almost colourless zone of complete combustion

hottest part

Bunsen burner

Non-Luminous flame

Must learn how to draw and label the parts

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- 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.

Strike Back

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How to Heat 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 Bunsen burner is then placed under the tripod stand and lighted.- The beaker is

removed fromthe flame whenthe liquid startsto boil.