4.9 Chemistry of the Atmosphere

Question 1

Explain why octane is a hydrocarbon(1)

Answer 1

contains only carbon and hydrogen

Question 2

How does burning coal affect the amount of carbon dioxide in the Earth’s
atmosphere? (2)

Answer 2

Increases the amount of carbon dioxide because there is carbon in coal, which reacts with oxygen to form carbon dioxide.

Question 3

Why is it important to stop carbon monoxide (CO) from being released into the air? (1)

Answer 3

harmful/poisonous

Question 4

Suggest why burning wood in power stations is said to be ‘carbon-neutral’. (2)

Answer 4

Carbon dioxide is produced from burning wood, and carbon dioxide is used by trees in photosynthesis.

Question 5

Suggest two reasons why the world production of coal is predicted to increase (2)

Answer 5

oil is running out, plentiful supply

Question 6

Give a reason why sulfur dioxide is produced in a petrol engine. (1)

Answer 6

sulfur in petrol reacts with oxygen

Question 7

Carbon neutral means that there is no increase in the amount of carbon dioxide in
the atmosphere.
Suggest why adverts claim that using biodiesel is carbon neutral. (2)

Answer 7

burning biodiesel releases carbon dioxide and carbon dioxide is absorbed by the plants used to produce the biodiesel

Question 8

Explain why clearing large areas of forest has an environmental impact on the
atmosphere(2)

Answer 8

increases carbon dioxide because burning trees releases carbon dioxide

Question 9

Why is there an increasing demand for biodiesel?(1)

Answer 9

Crude oil is non-renewable

Question 10

Suggest why producing biodiesel from crops:

(i) causes ethical concerns
(ii) causes economic concerns

Answer 10

i) use crops that could be used for food

ii) increases the cost of food

Question 11

Biodiesel may be less suitable than petroleum diesel as a fuel for cars.
Use these results to suggest one reason why.

Answer 11

does not flow as easily through pipes

Question 12

What conclusions can the scientist make about the viscosity of biodiesel compared
with the viscosity of petroleum diesel at different temperatures?(2)

Answer 12

biodiesel is more viscous than petroleum diesel at all temperatures and in petroleum diesel the viscosity does not change

Question 13

Replacing petroleum diesel with biodiesel increases one type of environmental
pollution. Explain why (2)

Answer 13

increases acid rain because there is more nitrogen oxides

Question 14

is biodiesel a carbon neutral fuel? (2)

Answer 14

no because carbon dioxide is released and this will not all be absorbed by photosynthesis

Question 15

Suggest why burning wood instead of coal would help to reduce our carbon footprint(3)

Answer 15

Wood is renewable, no new carbon dioxide is produced and carbon dioxide is used by trees in photosynthesis

Question 16

Why is it so difficult to produce models for climate change?(1)

Answer 16

many alternative theories

Question 17

Describe how carbon dioxide helps to maintain temperatures on Earth(3)

Answer 17

Carbon dioxide allows short wavelength radiation to pass through the atmosphere to the Earth’s surface. Carbon dioxide absorbs outgoing long wavelength radiation

Question 18

Explain how human activities have contributed to the main trend shown from 1910 in the figure above (Global air)

Answer 18

General increase in temperature caused by increase in greenhouse gases. Increased burning of fossil fuels causes carbon dioxide. Deforestation causes more carbon dioxide

Question 19

Petroleum diesel is produced from crude oil. Biodiesel is produced from plant oils. The crops used to produce biodiesel can be used to feed humans. Evaluate the use of plant oils to produce biodiesel(5QWC)

Answer 19

• renewable
• burning biodiesel produces low amounts of particulates
• can use waste vegetable oils from the food industry
• creates food shortages
• crops take time to grow
• vast areas of land needed for crops to grow

Question 20

Explain how carbon monoxide would be formed(2)

Answer 20

Incomplete combustion of the fuel when there is insufficient oxygen to burn the fuel completely

Question 21

Explain the meaning of ‘locked up’ carbon dioxide (2)

Answer 21

Carbon dioxide from Earth’s early atmosphere was used to form sedimentary rocks

Question 22

Benefits of using biodiesel as a sustainable, low pollution fuel(3)

Answer 22

• renewable, use less fossil fuels/diesel

- less new carbon dioxide, most emissions are lower

Question 23

Why is biodiesel’s contribution to global warming considered as much less than fossil diesel (3)

Answer 23

Plants use carbon dioxide from the air, biodiesel releases carbon dioxide from plants. Fossil diesel releases ‘locked up’ carbon dioxide.

Question 24

Coal contains carbon and small amounts of sulfur. Explain the environmental problems if coal was used as a fuel (Steam train- 4)

Answer 24

global warming caused by the formation of CO2

acid rain caused by the formation of SO2

Question 25

If wood was used as a fuel, why would it be ‘carbon neutral’ steam train

Answer 25

renewable, no ‘new’ carbon dioxide is produced and carbon dioxide is used by trees in photosynthesis.

Question 26

Describe the natural processes which remove carbon dioxide from the atmosphere(4)

Answer 26

Plants take in carbon dioxide for photosynthesis, and carbon dioxide dissolves in seawater. It is also locked up in fossil fuels and used to form sedimentary rocks.

Question 27

Describe how carbon dioxide is released into the atmosphere: (4)

i) by human and industrial activity
ii) from carbonate rocks by geological activity

Answer 27

i) respiration, burning of fossil fuels

ii) rock is decomposed and carbon dioxide is released through volcanoes

Question 28

Explain how seas/oceans decrease the amount of carbon dioxide in the atmosphere(3)

Answer 28

Carbon dioxide dissolves in seawater producing insoluble carbonates and carbon dioxide formed and locked into shells/limestone

Question 29

The amount of carbon dioxide in the atmosphere is increased by reactions that occur in internal combustion engines (x) and is decreased by reactions in seawater (y). Describe in as much detail as you can, the reactions which take place at X and Y. (5)

Answer 29

X - combustion of fossil fuels

Y - produces calcium carbonate which is insoluble, photosynthesis which releases oxygen

Question 30

there is not much oxygen in the atmosphere of Mars. Suggest why

Answer 30

Mars has no living plants

Question 31

How is carbon dioxide released from limestone?(2)

Answer 31

calcium carbonate decomposed

CaCO3 → CaO + CO2

Question 32

Suggest why scientists don’t know the accurate composition of the Earth’s early atmosphere.

Answer 32

Humans had not evolved yet, millions of years ago

Question 33

There are other differences between Earth’s early atmosphere and the atmosphere of today. Use the bar charts to describe and explain 2 of these other differences(3)

Answer 33

carbon dioxide decreased from 95% to 0% because it was used by plants during photosynthesis
oxygen increased from 0% to 21% because it was released during photosynthesis

Question 34

Describe how volcanoes caused the oceans to be formed(2)

Answer 34

Water vapour was given out from volcanoes and condensed to form the oceans

Question 35

Wegener had an idea plates could move. Give one piece of evidence that led to Wegener’s idea being accepted(1)

Answer 35

Sea floor spreading

Question 36

Why can scientists not prove which theory about the core is correct? (1)

Answer 36

Cannot see the core

Question 37

Why should we be concerned about our global footprint(1)

Answer 37

thought to cause global warming

Question 38

The burning of fossil fuels has caused the percentage of carbon dioxide in the atmosphere to increase. Explain why (2)

Answer 38

Increased burning of fossil fuels means locked up carbon dioxide is released

Question 39

Explain why we should be concerned about the information displayed on this graph (increase of CO2) (3)

Answer 39

Increasing carbon dioxide, there is a more rapid increase recently and carbon dioxide causes global warming

Question 40

Describe and explain how the composition of Earth’s atmosphere was changed by the formation of coal. (3)

Answer 40

carbon dioxide decreased by plants, and oxygen increased by plants in photosynthesis. Coal locks up carbon dioxide, decreasing the amount of carbon dioxide.

Question 41

Explain how the use of calcium carbonate:

a) increases atmospheric pollution (2)
b) decreases atmospheric pollution (2)

Answer 41

a) carbon dioxide is released from the thermal decomposition of calcium carbonate
b) sulfur dioxide is removed by reaction with calcium carbonate

Question 42

How did nitrogen form(1)

Answer 42

Nitrogen formed because ammonia from Earth’s early atmosphere reacted with oxygen.

Question 43

Other than gases, what else may be released from burning fuels? (2)

Answer 43

solid particulates and unburned hydrocarbons

Question 44

Why does it rain methane on Titan?
methane boiling point -164 degrees C
average surface temperature of Titan is -178 degrees C
(2)

Answer 44

Because methane’s boiling point is greater than the average surface temperature, and any methane that evaporates will condense

Question 45

Why does the release of this carbon dioxide cause an environmental problem?(1)

Answer 45

increases global warming

Question 46

When the Earth was formed its atmosphere is thought to have been similar to the atmosphere on Mars. Explain how green plants and other organisms have changed the
composition of the Earth’s atmosphere(4)

Answer 46

Plants take up carbon dioxide and give out oxygen in photosynthesis. Nitrogen gas produced by reaction of oxygen and ammonia.

Question 47

Give one reason why the amount of carbon dioxide in the atmosphere is increasing
gradually. (1)

Answer 47

sea is unable to absorb all the extra carbon dioxide being produced

Question 48

Evaluate the three methods of removing sulfur dioxide from waste gases. Complete the three methods and give a justified conclusion (6)

Answer 48

W removes the most carbon dioxide and D removes the least carbon dioxide. Both W and D use calcium carbonate. Calcium carbonate is obtained by quarrying which will destroy habitats. D produces carbon dioxide which may cause global warming. S uses sea water which is readily available. W product can be sold, W also makes carbon dioxide which may cause global warming. S may pollute the sea and D waste fill landfill sites.

Question 49

Explain how the first seas were formed (2)

Answer 49

Water vapour from the atmosphere condensed to form the first oceans.

Question 50

Explain why excess carbon dioxide should be prevented from entering the atmosphere. (2)

Answer 50

Carbon dioxide is a greenhouse gas and carbon dioxide causes global warming.

Question 51

Describe what causes the Earth’s tectonic plates to move (3)

Answer 51

convection currents, radioactivity, releases heat

Question 52

A student was asked to use the data in the table to compare these four fuels, and then
place the fuels in an order.
The order that the student chose was:
Use the information in the table to suggest reasons why the student chose this order.
To gain full marks in this question you should write down your ideas in good English. Put
them into a sensible order and use the correct scientific words. (D,A,C,B) (4)

Answer 52

B is least energy efficient in terms of cost, D is 1st since it only gives water as a product. A is 2nd best since it produces carbon dioxide.

Question 53

Graph 1 shows how the percentage of carbon dioxide in the atmosphere changed in the
last 4500 million years.
Describe how the percentage of carbon dioxide has changed in the last 4500 million
years. (2)

Answer 53

carbon dioxide decreases rapidly at first then slowly

Question 54

Carbon dioxide is also a greenhouse gas.
The figure below shows how the concentration of carbon dioxide in the atmosphere has
changed since 1850.
Give three conclusions that can be made from the figure above (3)

Answer 54

1. carbon dioxide concentration stayed constant from 1850 to 1900
2. carbon dioxide concentration slowly increased from 1900
3. carbon dioxide concentration increased more rapidly from 1965

Question 55

Suggest one reason why there was no liquid water on the Earth’s surface billions of years
ago. (1)

Answer 55

the Earth’s surface temperature was high

Question 56

Figure 2 shows the carbon dioxide percentage (%) in the Earth’s atmosphere since the
year 1800.Describe, in detail, how the carbon dioxide percentage changed from 1900 to 2015 (2)

Answer 56

increased slowly then rapidly