science form 1 chapter 5
TRANSCRIPT
CHAPTER 5:
THE AIR AROUND US
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THE AIR AROUND USThe Earth is surrounded by a thick layer of air called the atmosphere Air is a mixture of gases and other component which is tasteless, colourless and odourless. Type of gases in air:
Nitrogen Oxygen Carbon dioxide Inert gases (argon, neon, helium, krypton, xenon, radon)
Other components: - water vapour, dust microorganisms
The composition of air varies from place to place and from time to timemaya_dgs2012
Atmosphere
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Why air is a mixture?
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Uses of gasesNitrogen preserve packaged foods Oxygen respiration, burning, rusting Carbon dioxide - photosynthesis
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Uses of inert gases
Helium for meteorological balloon
Xenon for sun lamps
Krypton for fluorescent bulbs.
For earthquake prediction
Neon for lightmaya_dgs2012
Composition of air
ComponentNitrogen Oxygen Carbon dioxide Inert gases & other substances
Percentage (%)78 21 0.03 0.97maya_dgs2012
Why air is a mixture?1.
2. 3.
The gases in the air can be easily separated (respiration, burning, rusting) Each gas in the air still maintain its original properties The ratio of the component in the air varies according to the condition of a place
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1)
2)3) 4)
LETS DO SOME EXPERIMENTS! What is the percentage of oxygen in the air? Does air contain water vapour? Does air contain microorganisms? Does air contain dust particles?
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Investigating the percentage of oxygen in the air
Procedure: 1) A candle is placed on gas jar stand in the trough and fill the trough with water 2) The gas jar are divided into five equal parts using rubber bands 3) The candle is lighted up and the gas jar is inverted over the lighted candle 4) The changes of water level is examined as the candle goes offmaya_dgs2012
Observation: -As the candle continue to burn the flame get smaller and finally it goes off - The water level in the gas jar rose until it reach one fifth of the marked height when candle goes off Conclusion: Oxygen makes up of approximately 21% of the volume of air.maya_dgs2012
To show air contains water vapour
Procedure: 1) Put some ice cubes into the boiling tube 2) Record the observation on the external surface of boiling tube after 15 minutes 3) Test the liquid on the external surface of boiling tube with dry cobalt chloride paper 4) If blue cobalt chloride paper turns to pink in colour, this proofs that the liquid is water.maya_dgs2012
Observation: - Water droplets that formed on the outer wall of the test tube can be clearly seen. - Collected liquid droplets has been tested with a blue cobalt chloride paper and the paper then turns to pink in colour, proofs that the liquid is water. Conclusion: Air contains water vapour.maya_dgs2012
To show air contains dustProcedure: 1) Prepare the materials as shown 2) Observed the cellophane tape with magnifying glass after a few days Observation: Dust can be seen on the sticky surface of glass slide. Conclusion : Air contains dust.
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To show air contains microorganisms
Before
After a few days
Observation: - Coloured spots of microorganisms (fungi and bacteria) are found on the surface of the nutrient agar after a few days Conclusion: Air contains microorganisms.maya_dgs2012
PROPERTIES OF GASESOXYGEN
CARBON DIOXIDEmaya_dgs2012
PROPERTIES OF OXYGEN & CARBON DIOXIDEOxygen and carbon dioxide are the two main gases that made up the air for sustaining life The properties of gases can be studied and observed by carrying out the following tests
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Test 1: Solubility in water
OXYGEN Observation: The water level in the test tube rises slightly
CARBON DIOXIDE Observation: The water level in the test tube rises slightly (but more than oxygen) Conclusion: Carbon dioxide is slightly soluble in watermaya_dgs2012
Conclusion: Oxygen is slightly soluble in water
Test 2: Reaction with sodium hydroxide
OXYGEN Observation: The level of sodium hydroxide solution in the test tube does not change Conclusion: Oxygen is not soluble in sodium hydroxide
CARBON DIOXIDE Observation: The level of sodium hydroxide solution in the test tube rises a lot Conclusion: Carbon dioxide is very soluble in sodium hydroxidemaya_dgs2012
Test 3: Glowing wooden splinter
OXYGEN Observation: The glowing wooden splinter bursts into flame (relights/rekindless) Conclusion: Oxygen supports combustion
CARBON DIOXIDE Observation: The glowing wooden splinter extinguished (goes off) Conclusion: Carbon dioxide does not supports combustionmaya_dgs2012
Test 4: Burning wooden splinter
OXYGEN Observation: The burning wooden splinter burns brightly
CARBON DIOXIDE Observation: The burning wooden splinter extinguished (goes off) Conclusion: Carbon dioxide does not supports combustionmaya_dgs2012
Conclusion: Oxygen supports combustion
Test 5: Tested with moist litmus paper
OXYGEN Observation: The colour of both litmus paper does not change Conclusion: Oxygen is neutral
CARBON DIOXIDE Observation: The colour of blue litmus paper turns red Conclusion: Carbon dioxide is acidic
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Test 6: Lime water test
Lime water
OXYGEN Observation: No change in lime water (remains clear) Conclusion: Oxygen has no effect on lime water
CARBON DIOXIDE Observation: The lime water turns cloudy (chalky) Conclusion: Carbon dioxide turns the lime water cloudy maya_dgs2012
Test 7: Bicarbonate indicator test
Control
Oxygen
Carbon dioxide
OXYGEN Observation: The colour of bicarbonate indicator does not change Conclusion: Oxygen is neutral
CARBON DIOXIDE Observation: The colour of bicarbonate indicator turns yellow Conclusion: Carbon dioxide is acidic
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PROPERTIES OF OXYGEN
Colourless, tasteless & odourless Slightly soluble in water Not soluble in sodium hydroxide No effect on damp litmus paper No effect on lime water Relights a glowing splinter No effect on hydrogen carbonate solution Support combustion Neutral
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PROPERTIES OF CARBON DIOXIDE
Colourless, tasteless & odourless More soluble in water Very soluble in sodium hydroxide Turns blue litmus paper to red Turns lime water cloudy Extinguishes a burning splinter Changes the colour of hydrogen carbonate from red to yellow Does not support combustion Acidic
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COMPARISON BETWEEN OXYGEN & CARBON DIOXIDEPROPERTIES Colour Odour Taste Solubility in water Solubility in sodium hydroxide OXYGEN Colourless Odourless Tasteless Slightly soluble CARBON DIOXIDE Colourless Odourless Tasteless Slightly soluble
Not soluble
Very soluble
Effect in glowing splinter
Relight the glowing splintermaya_dgs2012
The splinter goes out (extinguishes)
COMPARISON BETWEEN OXYGEN & CARBON DIOXIDEPROPERTIES OXYGEN CARBON DIOXIDE
The splinter burns brighter (oxygen support burning Effect on moist No change in both litmus paper litmus paper (oxygen is neutral) Effect on No change limewater Effect on No change hydrogen carbonate
Effect in burning splinter
The splinter goes out (extinguishes)Blue litmus paper turns red (carbon dioxide is acidic) Limewater turns cloudy Red colour turns yellow (carbon dioxide is acidic)
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COMFIRMATION TEST FOR OXYGEN & CARBON DIOXIDEGAS Oxygen Carbon dioxide COMFIRMATION TEST Glowing splinter Limewater OBSERVATION Relights a glowing splinters Limewater turns cloudy
Oxygenmaya_dgs2012
Carbon dioxide
OXYGEN IS NEEDED FOR RESPIRATIONAll living things obtain energy when the food they have consumed is broken down Respiration = the chemical process in which energy is released from breaking down of food. Respiration required oxygen. Oxygen oxidises the glucose in the body cells to release energy Carbon dioxide, water vapour and energy are the product of respirationmaya_dgs2012
Respiration
Glucose
Carbon dioxide Water vapour
Oxygen
Energy
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To show living things use oxygen during respiration
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To show living things use oxygen during respirationObservation : - The drop of coloured water in tubes A and B move towards the tube. Discussion : - Cockroaches and germinating seeds (living things) take in oxygen and give out carbon dioxide during respiration. - Carbon dioxide is absorbed by sodium hydroxide. - Low pressure inside tubes make the higher pressure outside pushes the drop of coloured water towards the tubes. Conclusion: - Living things used oxygen during respiration.maya_dgs2012
To show that living things give out carbon dioxide during respirationObservation : - The colour of hydrogen carbonate indicator in tubes P and Q change from red to yellow. Discussion : - Cockroaches and germinating seeds (living things) give out carbon dioxide during respiration. - Hydrogen carbonate indicator absorbs the carbon dioxide and changes colour from red to yellow.We can use lime water to test the present of carbon dioxide Lime water turns cloudy in P and Q
Conclusion: - Living things give out carbon dioxide during respiration.maya_dgs2012
Inhaled and Exhaled Air
Inhaled air the air that is breathed in during respiration. Exhaled air the air is breathed out during respiration.
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Composition of Inhaled Air and Exhaled AirGas Nitrogen Inhaled air 78% Exhaled air 78%
OxygenCarbon dioxide Inert gases Water vapour
21%0.03% 0.97% Lesser
16%4% 0.97% More
Summary:- The composition of oxygen in inhaled air is higher than in exhaled air - The composition of carbon dioxide in exhaled air is higher than in inhaled airmaya_dgs2012
Comparing Inhaled and Exhaled AirTest by using lime water Test by using bicarbonate indicator
Inhaled Air
Exhaled Air
Inhaled Air
Exhaled Airmaya_dgs2012
OXYGEN IS NEEDED FOR COMBUSTION (BURNING)Combustion is a chemical reaction between fuel and oxygen which produce heat and light energy Condition for combustion are : - Oxygen - Heat - Fuelmaya_dgs2012
Substances (fuel) that can be burn easily include:-
Organic substances alcohol, ether, xylene Carbon charcoal, coal Hydrocarbon petrol, diesel, kerosene, candles, butane The product of combustion depend on the type of fuel used
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Fuel Organic Substances
Alcohol
Ether
Xylene
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Fuel Carbon
Coal
Charcoal
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Fuel Hydrocarbon
Petrol & Diesel
Kerosene
Butane
Cooking gasmaya_dgs2012
Candle
Product of combustionCombustion of carbon- Produces carbon dioxide,heat and light. Example: Charcoal + Oxygen Carbon dioxide + Heat + Light
Combustion of hydrocarbon-Produces carbon dioxide, water, heat and light.Example: Kerosene + Oxygen Carbon dioxide + Water + Heat + Lightmaya_dgs2012
Product of Combustion (Carbon)
Coal
Charcoal
Combustion of carbon- Produces carbon dioxide,heat and light. Example: Charcoal + Oxygen Carbon dioxide + Heat + Lightmaya_dgs2012
Product of Combustion Hydrocarbon)Petrol & DieselButane Kerosene
Cooking gas
Candle
Combustion of hydrocarbon-Produces carbon dioxide, water, heat and light.Example: Kerosene + Oxygen Carbon dioxide + Water + Heat + Lightmaya_dgs2012
EXPERIMENT TIME!!!!
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To show that oxygen is needed for combustionObservation : The candle inside the gas jar goes out after a short while. The candle outside the gas jar continues to burn Conclusion: - Oxygen is needed for combustion.maya_dgs2012
To investigate the effect of the size of a container on the length of time a candle burns.
Observation: The candle in the 500 ml beaker goes out first. The candle in the 1000 ml beaker continues to burn for some time before it goes out. Conclusion: The bigger the size of container, the longer the time for candle to burn. maya_dgs2012
To investigate the product of combustion (Carbon)
Charcoal Lime water
Observation & Discussion : Gas jar becomes hot The lime water turns cloudy because the presence of carbon dioxide Conclusion: The burning of carbon produces carbon dioxide, heat and light.maya_dgs2012
To investigate the product of combustion (Hydrocarbon)Cobalt chlorid e paper Lime water
Observation & Discussion: The funnel becomes hot The dry cobalt chloride paper changes colour from blue to pink to prove that water is present The lime water turns cloudy because the presence of carbon dioxide Conclusion: The burning of hydrocarbon produces carbon dioxide, water vapour, heat and light.maya_dgs2012
Importance Of CombustionIndustry Burning of fuel to generate electricity in power station. Boiling water to produce steam to turn the turbines. Transportation Burning of petrol or diesel in engines to move the vehicles. Burning the kerosene in aircraft engine to produce energy to fly.
Others Burning of candles as source of light. Burning of natural gas for cooking.
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Methods To Put Out A FireRemove fuel - Take away fuel from fire source. Remove oxygen supply - Using fire blanket, sand, cloth, fire extinguisher Remove heat - Using watermaya_dgs2012
What will you do if you on fire?
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AIR POLLUTIONAir pollution occurs when air contains pollutants Pollutants are substances that are released into the environment. These substances are harmful to living things and pollute the environment Air pollution is the result of human actionmaya_dgs2012
Dust Smoke , soot, smog Carbon dioxide
Sulphu r dioxide
Air pollutants
Carbon monoxid eLead compound s
Oxides of nitrogen
Chlorofluorocarbonsmaya_dgs2012
Open burning Smoking Motor vehicles
Sources of air pollutantsIndustrial activities
Construction activities
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Haze
Depletion of ozone layer
Effect of air pollution
Acid rain
Global warmin gmaya_dgs2012
Sources and effect of air pollutants on human being and the environmentAir pollutant Smoke particles and soot. Sources - Cigarette smoke. - Smoke from motor vehicles. - Burning of rubbish. - Burning of fossil fuels. - Forest fires - Construction sites - Open burning - Cigarette smoke - Smoke from motor vehicles Effects - Cause breathing difficulties. - Make the eyes feel uncomfortable.
Dust / haze
- Causes lung cancer, coughing and asthma. - Causes tiredness, headache, brain damage and death.maya_dgs2012
Carbon monoxide
Air pollutant Sulphur dioxide
Sources Burning of coal
Effects Damages lung cells Forms acid rain that damages Metallic structures and kills aquatic life Kills plants Form acid rain Causes damage to the ozone layer. Too much exposure to UV rays can cause, skin cancer, eye diseases and the break-down of the bodys immune system Causes green house effect Will result global warming, changes in climate, rising sea levels/ floodingmaya_dgs2012
Oxides of nitrogen Chlorofluorocarbon (CFC)
Smoke from motor vehicles -Aerosol spray, - electronics factories
Carbon dioxide
-Motor vehicles and factories -Open burning
Acid Rain
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Why Earth becomes hotter?
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Effect of greenhouse effect
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Effects Of Global WarmingAltering the climate on Earth Upsetting the balance of nature Destroying the beauty of nature & habitat Disrupting natural cycles (water cycle, oxygen cycle, carbon cycle)
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Effect of global warming
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Depletion of ozone layer
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Effect of depletion of ozoneHuman Health Damages DNA which suppresses immune system resulting in increase of infectious diseases Skin cancer Eye cataracts Plants and Trees Reduces crop production, damage to seeds Reduces quality of crops Aquatic Ecosystems Damage to plankton, aquatic plants, fish larvae, shrimp, crabs Affects marine food chain, damage to fisheries result Materials Paints, rubber, wood and plastic are degraded faster, especially in tropical regions Damages could be in billions of money annuallymaya_dgs2012
Do you want to live like these?
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Or like these?
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Avoid open burningPlanting a lot of trees
Enforcing anti-air pollution laws.
Steps to prevent airPractice carpooling or use public transport.
Do not smoke
Relocate factories away from urban areas Encourag e the use of biodiesel or unleaded fuel in vehicles Limit the use of CFC in industry
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THE IMPORTANCE OF KEEPING THE AIR CLEANAir is one of the basic needs of life. 2. A clean environment is important for survival of human beings and others living organisms 3. A clean environment guarantees the general good health of the community because all living things breathe in air 4. Air pollution affects health and causes respiratory diseases, skin diseases, eye and lungs irritations and cancer1.maya_dgs2012
The end.. =)
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Do you want to get band 6?
Evidence : B6D5E1 Make a presentation about: 1) Air pollution 2) Examples and sources of air pollutant 3) Effect of air pollution 4) Steps to prevent & control air pollution 5) Suggest ways to keep the air clean 6) Practice habits to keep the air cleanmaya_dgs2012
Conditions1. Presentation form:- Manila card or - Powerpoint presentation or - Video or others 2. Present by group of students - Max : 4 students - Min : 2 students 3. Time to prepare - 2 weeks (present after August exam) 4. Language used: - English / Bahasa Melayumaya_dgs2012
Membuat perbentangan dalam pelbagai bentuk mengenai: 1. Pencemaran udara 2. Contoh bahan cemar udara dan sumber 3. Kesan pencemaran udara 4. Langkah-langkah untuk menghalang dan mengawal pencemaran udar 5. Cara mengekalkan udara supaya bersih 6. Mempraktikkan amalan yang mengekalkan udara bersihmaya_dgs2012