How did fossil fuels form?

From the remains of dead organisms buried for millions of years under heat and pressure.

What is a hydrocarbon?

A compound containing only hydrogen and carbon.

Why are fossil fuels non-renewable?

They form over millions of years but are used far faster, so they will run out.

What is the word equation for complete combustion of a hydrocarbon?

Hydrocarbon + oxygen → carbon dioxide + water.

Word equation for the complete combustion of methane.

Methane + oxygen → carbon dioxide + water.

What are the possible products of incomplete combustion?

Water, carbon monoxide and/or carbon (soot).

What colour is the Bunsen flame with the air hole open and with it closed?

Open: blue and hot. Closed: yellow and sooty.

Why is carbon monoxide dangerous?

It is toxic: it stops the blood carrying oxygen, and it has no colour or smell.

Name two sources of carbon monoxide.

Faulty gas appliances and burning charcoal or fuel in a closed room (also car engines).

How do you test for carbon dioxide?

Bubble the gas through limewater; it turns cloudy.

Black particles of carbon made in incomplete combustion.

How can carbon monoxide poisoning be prevented?

Service gas appliances, ventilate rooms and fit carbon monoxide alarms.

Combustion and fuelsIB MYP Chemistry: Flashcards

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Name the three fossil fuels.

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Name the three fossil fuels.: Coal, crude oil and natural gas.
How did fossil fuels form?: From the remains of dead organisms buried for millions of years under heat and pressure.
What is a hydrocarbon?: A compound containing only hydrogen and carbon.
Why are fossil fuels non-renewable?: They form over millions of years but are used far faster, so they will run out.
What is the word equation for complete combustion of a hydrocarbon?: Hydrocarbon + oxygen → carbon dioxide + water.
Word equation for the complete combustion of methane.: Methane + oxygen → carbon dioxide + water.
What are the possible products of incomplete combustion?: Water, carbon monoxide and/or carbon (soot).
What causes incomplete combustion?: A limited supply of oxygen.
What colour is the Bunsen flame with the air hole open and with it closed?: Open: blue and hot. Closed: yellow and sooty.
Why is carbon monoxide dangerous?: It is toxic: it stops the blood carrying oxygen, and it has no colour or smell.
Name two sources of carbon monoxide.: Faulty gas appliances and burning charcoal or fuel in a closed room (also car engines).
How do you test for carbon dioxide?: Bubble the gas through limewater; it turns cloudy.
What is soot?: Black particles of carbon made in incomplete combustion.
How can carbon monoxide poisoning be prevented?: Service gas appliances, ventilate rooms and fit carbon monoxide alarms.

Exam questions on Combustion and fuels

A family in Istanbul cooks on a gas hob that burns methane (natural gas). The flame is normally blue. One evening the flame turns yellow and black soot appears on the bottom of the pans. An engineer finds that the air holes of the burner are blocked.
Explain why the flame turned yellow and left black soot on the pans.2 marks
A student in Lagos investigates the products made when ethanol burns in a spirit burner. She uses a pump to draw the waste gases through a U-tube surrounded by ice, and then bubbles the remaining gas through limewater. A colourless liquid collects in the U-tube and the limewater turns cloudy.
Write the word equation for the complete combustion of ethanol.2 marks
Crude oil and natural gas are fossil fuels. They are found under the seabed in countries such as Norway and are burned in power stations, vehicles and homes.
Describe how crude oil and natural gas were formed.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).