C9 - chemistry of the atmosphere

Question 1

What percentage of nitrogen is present in the current atmosphere?

Answer 1

Approximately 80%

Question 2

What percentage of oxygen is present in the current atmosphere?

Answer 2

Approximately 20%

Question 3

Which gases, other than nitrogen and oxygen, are present in the current atmosphere?

Answer 3

· Carbon dioxide
· Water vapour
· Methane
· Noble gases

Question 4

Describe Earth’s atmosphere 4.6 billion years ago.

Answer 4

Carbon dioxide was abundant but there was no oxygen.

Question 5

Why is it difficult to give evidence for Earth’s early atmosphere?

Answer 5

It was a long time ago (4.6 billion years).

Question 6

Describe and explain how Earth’s atmosphere has changed from 4.6 billion years ago.

6 marks

Answer 6

· Volcanic activity was high, causing high concentrations of carbon dioxide and water vapour to be present. There was no oxygen due to a lack of plants
· Water vapour condensed, forming oceans
· Carbon dioxide dissolved in oceans, forming fossil fuels. Carbonates precipitated to form sediments
· Algae evolved, photosynthesising which used up carbon dioxide and produced oxygen
· Animals evolved, which ate plants and respired. This slightly increased carbon dioxide levels

Question 7

What is the word equation for photosynthesis?

Answer 7

carbon dioxide + water —-> oxygen + glucose

Question 8

What is the symbol equation for photosynthesis?

Answer 8

6CO2 + 6H2O —-> 6O2 + C6H12O6

Question 9

Name 3 greenhouse gases.

Answer 9

· Carbon dioxide
· Methane
· Water vapour

Question 10

Explain the greenhouse effect.

Answer 10

· Short wavelength solar radiation enters the Earth’s atmosphere
· It reflects off of the Earth, and travels back towards space as long wavelength solar radiation
· Some long wavelength solar radiation escapes and returns to space
· Some is trapped and absorbed by greenhouse gases, increasing the temperature of the Earth.

Question 11

How do humans increase the concentration of carbon dioxide in the atmosphere?

Answer 11

· Combustion of fossil fuels
· Deforestation
· Respiration

Question 12

How do humans increase the concentration of methane in the atmosphere?

Answer 12

· Rice farming
· Landfill
· Cattle rearing

Question 13

Why is it difficult to predict rate of climate change?

Answer 13

There are a vast number of different factor affecting it.

Question 14

State some effects of climate change.

Answer 14

· Melting ice caps (leads to rising sea levels)
· Habitat loss
· Exacerbated natural disasters
· Increased global temperatures

Question 15

How is sulfur dioxide produced?

Answer 15

Sulfur impurities in coal are combusted.

Question 16

How are carbon particulates produced?

Answer 16

Incomplete combustion.

Question 17

How is carbon monoxide produced?

Answer 17

Incomplete combustion.

Question 18

How are oxides of nitrogen produced?

Answer 18

Nitrogen reacts with oxygen at high temperatures in car engines.

Question 19

What effect does sulfur dioxide have on the environment?

Answer 19

Acid rain

Question 20

What effect do carbon particulates have on the environment?

Answer 20

Global dimming

Question 21

What effect does carbon monoxide have?

Answer 21

Toxic

Question 22

What effect do oxides of nitrogen have?

Answer 22

Cause respiratory issues