Chapter 5 form1
Transcript of Chapter 5 form1
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CHAPTER 5
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Content
Activity
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The layer of air
surrounding the Earthconsists of a mixture ofgases.
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Air
Gases
Nitrogen
Carbon
Dioxide
Oxygen
Inert Gases
Othercomponents
Dust
Microorganisms
Water
Vapour
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Gas Percentage of gas content
Nitrogen 78%
Oxygen 21%
Carbon dioxide 0.03%
Inert gases and others 0.97%
Nitrogen
Oxygen
Carbon dioxide
Inert gases and
others
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An inactive gas.
Colourless, no smelland no taste.
Necessary for respiration,burning, rusting, and decay.
Released during respiration,burning and decay.
Absorbed by green plantsduring photosynthesis.
Example of inert gases are
helium, argon, neon, xenon,radon and krypton.
All these gases are nonreactive.
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When we leave a slice of bread outin the open for several days, what
happens to the bread?
The bread will turn mouldy. Themould shows the presence of
microorganisms in the air.In this case the fungi spores havesettled and started growing on thebread.
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The properties of oxygen and carbon dioxideProperties Oxygen Carbon dioxide
Solubility in water Slightly soluble Slightly soluble
Solubility in sodiumhydroxide solution
Not soluble Very soluble
Effect on glowingwooden splinter
The splinter ignites Oxygen supports burning
The splinter goes out Carbon dioxide does notsupport burning
Effect on burningwooden splinter
The splinter burns brighter Oxygen supports burning
The splinter goes put Carbon dioxide does notsupport burning
Effect on moist bluelitmus paper or moistred litmus paper
Oxygen has no effect onblue litmus paper or redlitmus paper
Oxygen is a neutral gas
Blue litmus paper : changesto red Red litmus paper : no change
of colour Carbon dioxide is an acidicgas
Effect on lime water No change Lime water turns cloudy
Effect onbicarbonate indicator
No change Changes the colour ofbicarbonate indicator fromred to yellow
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5.3 Oxygen is needed in respiration
oxygen
Food(sugar)
energy
Carbondioxide
water
1. The process where our body obtains energy from food is called respiration .2. During respiration , food in the form of sugar is oxidised by oxygen .3. The products of respiration are energy , carbon dioxide , and water vapour .4. Living things use the energy to carry out living processes such as breathing , moving
and reproduction.5. Carbon dioxide and water vapour are waste products that need to be removed from
the body .6. Living things obtain the oxygen needed for respiration through breathing .7. During breathing , living things take in oxygen from the air and remove carbon
dioxide and water vapour .
8. This explain s why the content of oxygen is more in inhaled air than in exhaled air.
Cell respiration requires oxygen
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5.4 oxygen is needed for
combustion
Combustion is a fast chemical reaction
between a substance and oxygen .
Oxygen supports combustion .
Combustion will only take place under
the following condition :
The presence of oxygen
The precence of fuel
Enough amount of heat is present
Heat energyLight energy
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What are the products of
combustion ?
Carbon + oxygen heat energy + light energy + carbon doixidecombustion
Hydrocarbon + oxygen heat + light + carbon + waterenergy energy dioxide
combustion
Conditions for combustion
Fuel
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5.5 Air pollution
Pollutants Effects
Dust
Soot
Smoke
Air become hazy
Low visibility
Breathing difficulties
Reduction in the rate of photosynthesis
Lead Damage to the brain or kidney
Carbon dioxide The temperature of the earth to rise
Sulphur dioxide
Nitrogen oxideTo form acid rain
Chlorofluorocarbon (CFC) Damage to the ozone layer
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Hello human !
We can prevent and control airpollution consist of two strategies ,
namely enforcement of anti-pollutionlaws and managing pollutants
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5.6 the importance of keeping the
air clean
Habits
that keep
the air
clean
You should
reduce short
trips . Walk .
Do not
smoke
Turn off the
engine of thecar while
waiting for
someone .Send your
motor vehicles
for regular
service to
reduce outputof polluting
exhaust gases .
Do notpractice open
burning .
Dispose of
your garbage
carefully
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