Chemistry of the Atmosphere

Question 1

How did the oceans form?

Answer 1

Volcanic activity released gases such as water vapour and carbon dioxide. As the Earth cooled, water vapour condensed, fell as rain, and formed oceans.

Question 2

How did the levels of oxygen increase?

Answer 2

When algae and plants photosynthesise, oxygen is released. As more photosynthetic organisms evolved, CO₂ levels decreased and oxygen levels increased.

Question 3

How did carbon dioxide levels decrease?

Answer 3

Fossil Fuels:
Coal formed from plants
Crude oil and natural gas formed from plankton and algae
They contained carbon compounds formed from the glucose formed in photosynthesis.
Sedimentary Rocks:
Carbon dioxide is a soluble gas and dissolved in the Earth’s early oceans.
Dissolved CO₂ releases carbonate ions which react with dissolved metal ions to form insoluble carbonates
Over millions of years these became sedimentary rocks.

Question 4

Explain how coal deposits formed.

Answer 4

Trees died and were buried under sediment. Their remains were exposed to high pressures and temperatures and were converted to coal over millions of years.

Question 5

Name three greenhouse gases.

Answer 5

Carbon dioxide, methane and water vapour.

Question 6

What is the greenhouse effect?

Answer 6

Greenhouse gases hero the Earth Warner than it would be without them and keep its temperature high enough for life to exist.

Question 7

What are the steps that happen in the greenhouse effect?

Question 8

How do human activities release carbon dioxide?

Answer 8

Burning fossil fuels and cement manufacture.

Question 9

How do human activities release methane?

Answer 9

Cattle farming (decaying animal and plant waste)
Coal mining and oil and gas production

Question 10

What is peer reviewed scientific evidence?

Answer 10

It is evaluated by other scientists. This means that findings submitted by a scientist or research group are checked before being accepted or rejected.

Question 11

What do increasing global temperatures cause?

Answer 11

Climate change

Question 12

What are some of the results of global warming?

Answer 12

More heat waves
More droughts in some places
Fewer cold periods
Increased rainfall in some places

Question 13

Give two reasons why climate change is leading to increased sea levels.

Answer 13

As the oceans warm up they expand.
Water from melting ice in the Antarctic and in glaciers flows into the oceans.

Question 14

Why do some people not believe climate change is happening?

Answer 14

They may only think about parts of the evidence which may be biased.

Question 15

What is carbon footprint?

Answer 15

A measure of someone’s greenhouse gas emissions.

Question 16

How can governments encourage reductions in carbon footprint?

Answer 16

They can pass laws to ban or control the use of products, services or events that release a lot of greenhouse gases. They can reduce facts on things with low carbon footprints.

Question 17

What are atmospheric pollutants?

Answer 17

Harmful substances released into the air.

Question 18

What are the properties and problems with carbon monoxide?

Answer 18

Odourless, colourless, toxic.
Causes breathing difficulties and can be fatal.

Question 19

What are the properties and problems of unburnt hydrocarbons?

Answer 19

Form soot and other particles.
Causes breathing problems and global dimming.

Question 20

Describe how the formation of limestone decreases the percentage of carbon dioxide in the Earth’s atmosphere.

Answer 20

Carbon dioxide from the atmosphere dissolved in the oceans where it reacted to form carbonates - these were used by organisms to form their carbonate-containing shells and skeletons. When the sea animals died their shells and skeletons fell to the sea bed and became compressed, forming limestone. The carbon dioxide was therefore locked up in the limestone instead of being on the atmosphere.

Question 21

Suggest how carbon particulates may reduce the extent of global warming.

Answer 21

Particulates in the atmosphere cause global dining by reflecting sunlight back into space which reduces the amount of energy from the sun that makes it to the Earth’s surface. This means there is less energy that can become trapped in our atmosphere and contribute towards global warming.

Question 22

How is Nitrogen oxide produced in the engine of a car that burns fossil fuels?

Answer 22

At high temperatures in the engine of the car nitrogen reacts with oxygen to produce nitrogen oxide.