Fossil Fuels/ pollutants

Question 1

How is coal formed over millions of years?

Answer 1

• Plant matter gets covered with sediment/ dirt and gets compressed.
• High temp/ Pressure = coal.

Question 2

How is crude oil formed over millions of years?

Answer 2

• Plankton and marine organisms
• Fall to bottom of sea- bed
• Compressed by sediment/ dirt
• Heat/ pressure converts them into crude oil

Question 3

How is natural gas formed over millions of years?

Answer 3

• Similar way to crude oil.
• Higher temperature/ pressure.

Question 4

How has the formation of fossil fuels decreased the amount of CO₂ in the atmosphere?

Answer 4

• Carbon is trapped in the fossil fuels.
• Carbon was part of CO₂ taken in by photosynthesis by plankton/ plant.

Question 5

What is a fuel?

Answer 5

• Fuels are substances that release energy when combusted (burned.)

Question 6

What do most fuels, including coal, contain in them?

Answer 6

• Carbon/ or hydrogen
• May contain sulphur.

Question 7

What happens to the carbon and hydrogen atoms in coal and hydrocarbons when we burn them?

Answer 7

• They react with oxygen in the air.
• They are oxidised.

Question 8

What is the word equation for complete combustion of methane?

Answer 8

Fuel (eg.methane) + oxygen –> carbon dioxide + water vapour

Question 9

What is needed in order for complete combustion to take place?

Answer 9

• Plenty of oxygen is needed for complete combustion.

Question 10

What is the word equation for incomplete combustion of methane?

Answer 10

• Methane + Oxygen –> Carbon monoxide + water vapour

Question 11

When does incomplete combustion take place?

Answer 11

• When there is insufficient oxygen.

Question 12

Give an example of a fuel that contains sulphur.

Answer 12

• Coal contains sulphur

Question 13

What happens to the sulphur in coal when it is burnt?

Answer 13

• Sulphur atoms are oxidised.
• This forms the gas sulphur dioxide.

Question 14

What is the effect of CO₂ released in complete combustion?

Answer 14

• It is a greenhouse gas. So burning fuels that release CO₂ leads to climate change.

Question 15

What is the effect of CO produced by incomplete combustion?

Answer 15

• Toxic gas, no colour/ smell.
• Displaces oxygen, binds to hemoglobin.

Question 16

How are oxides of nitrogen produced?

Answer 16

• Produced in car engines.
• High temperatures cause O₂ and N₂ in the air to react.
• This forms a range of different molecules. Scientists call them oxides of nitrogen.

Question 17

What are the effects of sulphur dioxides and oxides of nitrogen?

Answer 17

1.) Breathing problems in humans.
2.) Both dissolve in rainwater to form acid rain.

Question 18

Give 2 effects of acid rain.

Answer 18

• Erode limestone buildings
• Damage trees.

Question 19

Other than CO what elese can be produced by incomplete combustion?

Answer 19

• Soot (particles of carbon)
• Unburned hydrocarbons.

Question 20

What type of polution are solid particles and unburned hydrocarbons?

Answer 20

-Particulates

Question 21

What are the 2 effects of particulates?

Answer 21

• Damage human health ie. increase risk of lung/ heart disease.
• Reduce amount of energy from sun that reaches earth’s surface –> global dimming.
• Global dimming = less photosynthesis