الأسبوع 19 · المحور الثالث، الوحدة الثالثة، المفهوم 3.2 «الوقود وأنواعه» (ب): الوقود الأحفوري والتلوث وترشيد الاستهلاك · 3 دروس
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How fossil fuels formed
Discovery Education Science P4: Term 2, Unit 3, pp. 40–55
GoalPut the steps of fossil fuel formation in order and say what coal, oil and natural gas are used for.
New words
remains · what is left of a living thing after it diespressure · a strong push from all sides, here from layers of mud and rockgenerate · to make, for example electricity
Explanation
Fossil fuels formed in four steps. First, living things such as land plants and tiny living things in the sea lived a very long time ago, and they died. Second, their remains sank and were buried under mud and sand. Third, over millions of years more layers piled on top, and the heat and pressure of the Earth acted on the buried remains. Fourth, the remains slowly changed into coal, oil and natural gas. Each fuel is useful. Coal is burned in power plants and some factories. Oil is made into petrol and diesel for engines, and into other products. Natural gas is burned in kitchens and in power plants to generate electricity. All three store chemical energy that came from the Sun long ago. They cannot be made again in a human lifetime.
living things die→remains are buried→heat and pressure act for millions of years→coal, oil and gas
Worked examples
Letter
Step
A
heat and pressure act
B
oil forms
C
tiny sea living things die
D
remains are buried
Put these in order: A heat and pressure act, B oil forms, C tiny sea living things die, D remains are buried. The order is C, D, A, B.
A tanker brings oil to a refinery. From oil we get petrol for cars, diesel for buses and tractors, and other products. These are fossil fuels used for moving.
Natural gas flows through a pipe to a kitchen in Alexandria. It is burned on the cooker. The chemical energy changes to heat. The same gas also makes electricity in a power plant.
Class activity
Steps in order. Draw four small pictures with a grown-up: living things die; remains are buried; heat and pressure; coal, oil and gas. Cut them out, mix them and put them back in order with arrows. Say each step aloud. Then list three things at home that use fossil fuels.
Practice
1
What happens to the remains of ancient living things before they become fuel?
They are buried, and heat and pressure act on them for millions of years.
2
Which is made from oil: petrol or charcoal?
Petrol.
3
Match the fuel to its use. Say the letter of the fuel used in a kitchen.
