chapter 5 the air around us science form 1

7/27/2019 Chapter 5 the Air Around Us Science Form 1

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Science Form 1 note SMART STUDY - GOOD LUCK Teacher zaidi@maher2010

CHAPTER 5: AIR

Why is air a mixture ?

1. The composition of air is not fixed.2. It changes according to the time of the day, the

conditions of environment and humans activities.

3. For example, The air in a place which is crowded with people has a

higher content of a carbon dioxide than the air in a

less crowded place.

The air in a jungle has a higher content of oxygen thanthe air in an industrial area.

The content of water vapour in the air is higher in themorning than in the afternoon.

4. All these examples show that the percentage the

components

of air is not always the same.

5. Therefore, we can say that air is a mixture.

THE PROPERTIES OF OXYGEN AND CARBON DIOXIDE.

What are the properties of oxygen and carbon dioxide?

1. Oxygen and carbon dioxide are two of most importantgases in the air.

2. Table below shows the properties of oxygen and carbondioxide.

Properties Oxygen Carbon dioxide

Solubility in water. Slightlysoluble.

Slightlysoluble.


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Solubility in sodium

hydroxide solution. Not soluble. Very solubleEffect on glowing

wooden splinter.

The splinterignites.

Oxygensupports

burning.

The splintergoes out.

Carbon dioxidedoes not

support

burning.

Effect on burning

wooden splinter.

Splinter burnsmore brightly.

Oxygensupportsburning.

Splinter goesout.

Carbon dioxidedoes notsupport

burning.

Effect on moist blue

litmus paper and red

litmus paper.

Oxygen has noeffect on blue

litmus paper

and red litmus

paper.

Oxygen is aneutral gas.

Blue litmuspaper :

Changes to

red.

Red litmuspaper : Nochange of

colour.

Carbon dioxideis an acidic gas.

Effect on lime

water.

No change Lime waterturns cloudy.

Effect on

bicarbonateindicator.

No change Changes thecolour ofbicarbonate

indicator

from red to

yellow.


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OXYGEN IS NEEDED IN RESPIRATION

1. The process whereby our body obtains energy from foodis called respirations.

2. Respirations takes place in the cells of our body.3. Oxygen is needed for respiration to take place.4. The products of respirations are energy, carbon dioxide

and water vapour.

OXYGEN IS NEEDED FOR COMBUSTION

1.Combustion is a chemical reaction which takes place when fuelcombines with oxygen.

2.Fuel is a substance which can burn. For example :a. Carbon like charcoal, coal and firewood.b. Hydrocarbon like diesel, kerosene, gasoline (petrol),

candle and natural gas.

3.The product of fuel combustion :

a.

Carbon.Carbon + oxygen

carbon dioxide + light energy + heat energy.

b. Hydrocarbon.Hydrocarbon + oxygen -------- carbon dioxide +

water + light energy + heat energy.

AIR POLLUTION

1. Air pollution refers to the presence of foreign particlesin air which can affect the quantity of air and the health

of living things.

2. The sources and effects of air pollutants.


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Air pollutant Sources Effects

Smoke particles and

soot.

Cigarette smoke. Smoke from motor

vehicles.

Burning of rubbish. Burning of fossil fuels. Forest fires

Cause breathingdifficulties.

Make the eyesfeel

uncomfortable.

Dust Construction sites Cement plants

Causes lungcancer, coughing

and asthma.

Carbon monoxide Cigarette smoke

Smoke from motorvehicles

Causes tiredness,headache, braindamage and death.

Sulphur dioxide Burning of coal Damages lung cells Forms acid rain

that damages

metallic

structures and

kills aquatic life

Kills plantsOxides of nitrogen Smoke from motor

vehicles

Form acid rain

3. Steps to control air pollution. (pg.74)

THE IMPORTANCE OF KEEPING THE AIR CLEAN

1. Air is one of the basic needs of life.2. We would all suffer in many ways if they we no clean air

for us to breath:

It is unpleasant to smell dirty air. We may have breathing difficulties. We may cough continuosly.


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We may get lung diseases.3. We can help to keep the air clean by doing the following :

Using public transport. Using unleaded fuel. Enforcing anti-air pollution laws. Planting trees around the house.

4. Habits to keep the air clean : Do not smoke. Turn off the car engine while waiting for someone. Cycle or walk for short distance trips. Practice car-pooling.

chapter 5 the air around us science form 1

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