Download pdf - Form 1 science chapter 5 (part2)

SCIENCE Form 1

UNIT 5 .3 ,5.4

The Air Around Us1yschow88@smkbpj(a)

OXYGEN IS NEEDED FOR

5.3

NEEDED FOR RESPIRATION

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What is respiration?

The chemical process in which energy is released from the breaking down of food is called respiration.

• Where does• Where does

respiration take

place?

Respiration occur

in the body cells.4yschow88@smkbpj(a)

How does respiration take part?

• Respiration requires oxygen. Oxygen oxidises the glucose in the body cells to release energy.

• Carbon dioxide and water• Carbon dioxide and water

vapour are the waste products

in respiration:

Gucose Oxygen Energy Carbon dioxide

Water vapour

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Experiment to find the difference in oxygen content

between inhaled and exhaled air.

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What gas is needed for respiration?

• Responding- Contents of air in the boiling tube

• Constant- The presence of living organisms

• Manipulated- The position of mercury thread 8yschow88@smkbpj(a)

Result

• The mercury thread of A and B moves towards the boiling tubes.

• While the mercury thread at boiling tube C does not change. does not change.

Conclusion:

Oxygen is needed by animals and plants during respiration.

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Do organisms release carbon dioxide during respiration?

• Responding - Contents of air in the boiling tube

• Constant - The presence of living organisms

• Manipulated -The colour change carbonate indicator

(bicarbonate indicator) 10yschow88@smkbpj(a)

Result

The hydrogen carbonate indicator in tube X and Y change from redred to yellowyellow, while the hydrogen carbonate indicator in tubes Z does not change. Z does not change.

Conclusion

Organisms release carbon dioxide during respiration.

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Experiment to show the products of respirationExperiment to show the products of respiration




Check point




Humans require chemical energy to carry out life processes.

This energy is obtained when sugars from digested food are

broken down during respiration.

Summary so far :


Demand for energy


OXYGEN IS NEEDED FOR COMBUSTION

5.4


Combustion

Combustion is the burning of substances in air.

The substance (fuel), reacts rapidly with oxygen to produce heat and light.oxygen to produce heat and light.

Combustion is a chemical

process because during

this process new

substances are formed.


Conditions for combustion

Combustion can only occur when these three

conditions are satisfied, that is, the presence of:

a. a substance that can burn, or a fuel (2 types)

i. Carboni. Carbon

ii. Hydrocarbon

b. Oxygen

c. Heat to warm the fuel

until it reaches ignition

temperature.


The combustion of carbons

The combustion of

carbons like firewood,

charcoal and coal

produces carbon

dioxide and energy in dioxide and energy in

the form of heat and

light

Carbon + oxygen ��Carbon dioxide + energy


The combustion of hydrocarbons

The combustion of hydrocarbons which are

compounds of hydrogen and carbon, produces

carbon dioxide, water and energy in the form of

heat and light.

Examples of hydrocarbons:

1. Kerosene

2. Petrol

3. Diesel

4. wax.24yschow88@smkbpj(a)

The combustion of hydrocarbons

Hydrocarbon + oxygen �� Carbon dioxide + Water + energy



AIR POLLUTION

5.5


Substances that Pollute the Air

• Air pollution occurs when air contains pollutants.

• Pollutants are harmful substances harmful substances that are • Pollutants are harmful substances harmful substances that are released into the environment. released into the environment.

• Air pollution is the result of the acts of human.


Thinning of the ozone layer

• Chlorofluorocarbon (CFC)

form aerosol cans,

refrigerators, air

conditioners and

electronic factories.

• Destroys the ozone layer

in Earth's atmosphere

•• Ultraviolet light Ultraviolet light causes

cataracts and skin cancer

and skin cancer


• Nitrogen dioxide, nitrogen monoxide and sulphur

dioxide dissolve in rain drops to form acid rain.

Acid Rain


Acid Rain



THE IMPORTANCE OF KEEPING THE AIR CLEAN

5.6


• Nowadays many of our surrounding peoples are live in suffering of health problems such as lung cancer, asthma, skin disease, impaired of eye-sight and etc

• Accidents and breath problems increases due to air pollution such as haze

• Ways to keep the air clean:

i. Plant more trees at surroundingIi. Stop deforestationIi. Stop deforestationIii. Encourage habit of recycling by discarding materials made from

wood, plastic, glasses and tin


Ways to keep the air clean

iv. Practice car-pooling or prefer walking of short distance instead of driving

v. Practice using solar energy.

vi. Do not smokevi. Do not smoke

vii. Avoid open burning of waste products, such as rubbish

and plastics
