Chemistry of the Atmosphere

Question 1

What are the % for the gases in the atmosphere of the Earth today?

Answer 1

Nitrogen - 78%
Oxygen - 21%
Other gases (Carbon dioxide, water vapour, and noble gases such as argon) - 1%

Question 2

Why can scientists cannot be certain about the early atmosphere?

Answer 2

Because the Earth is 4600 million years old

Question 3

What do scientists think happened in the first billion years of Earth?

Answer 3

Intense volcanic activity, which these volcanoes released gases that formed the atmosphere such as water vapour and as the Earth cooled, the water vapour condensed to form the oceans. In addition, the volcanoes formed carbon dioxide which the Earth’s early atmosphere consisted mainly of carbon dioxide with little to no oxygen.

Question 4

What did the volcanoes produce?

Answer 4

-Nitrogen
-Water Vapour
-Small amounts of methane and ammonia
-Carbon dioxide

Question 5

What were the gases like in the Earth’s early atmosphere?

Answer 5

Mainly consisted of carbon dioxide with small but increasing amounts of nitrogen.

Question 6

How did the Earths early atmosphere transform into the atmosphere today?

Answer 6

-First, the water vapour from volcanoes condensed to form the oceans.
-At this stage, some of the carbon dioxide dissolved in the oceans to form a weak acid. This reacted with minerals in the sea to form precipitates.
-Over time, this formed sediments of carbonate rock on the sea bed.
-Some of the carbon dioxide in the sea was used to make corals and shells of organisms such as mussels. When theses died, they formed the sedimentary rock limestone. This also removed carbon dioxide from the atmosphere.
-And photosynthetic algae started to evolve in the oceans and photosynthesis produced oxygen which entered the atmosphere.
-The carbon can then be trapped in fossil fuels and again that caused the level of carbon dioxide in the atmosphere to fall.
-Over the following billion years, plants evolved increasing the amount of oxygen in the atmosphere. At some point the level of oxygen reached the point where animals evolved.

Question 7

How is coal formed?

Answer 7

Formed from the remains of ferns and trees and over time the plant remains are covered with sediment and are compressed. High temperature and pressure creates coal.

Question 8

What happens if the remains of ferns and trees die in marshy wetlands?

Answer 8

If these die in marshy wetlands then they do not decompose and that can be due to lack of oxygen or acidic conditions these both prevent bacteria from carrying out decomposition.

Question 9

How is oil formed?

Answer 9

Crude oil is formed from plankton which are tiny plants and animals found in the sea. When these die, they settle in mud on the sea-bed and if oxygen is not present then they do not decompose. Over time, they are compressed by sediment and heat and pressure then convert them into crude oil.

Question 10

How is natural gas formed?

Answer 10

We often find natural gas near deposits of oil that is because natural gas is formed from plankton in a similar way to oil.

Question 11

What does natural gas mainly consists of?

Answer 11

The hydrocarbon methane

Question 12

What do all fossil fuels contain?

Answer 12

Trapped carbon

Question 13

What are the main greenhouse gases?

Answer 13

Water vapour
Carbon dioxide
Methane

Question 14

What is it meant by the greenhouse effect in terms of short and long wavelength radiation?

Answer 14

-Energy from the sun travels to the Earth as short wavelength radiation (UV and Visible light).
-Some of the short wavelength radiation simply reflects back into space but most of it passes easily through the atmosphere that is because short wavelength radiation does not interact strongly with the gas molecules in the atmosphere.
-The energy of the radiation is absorbed when it reaches the surface of the Earth.
-The surface of the Earth now radiates the energy as long wavelength radiation (infra-red).
-Now some of the long wavelength radiation interacts with the greenhouse gas molecules in the atmosphere in other words the energy in the long wavelength radiation is absorbed.
-Because the energy is trapped in the atmosphere, this causes the temperature of the atmosphere to increase.

Question 15

Why is the greenhouse effect essential to life on Earth?

Answer 15

The greenhouse effect keeps the temperature on Earth warm enough to support life and without it the Earth would be too cold for most living organisms to survive.

Question 16

Why do we burn coal?

Answer 16

-For electricity.
-Petrol and diesel to power cars.
-Gas to heat our homes.

Question 17

Why is deforestation happening?

Answer 17

To provide land for grazing cattle

Question 18

What does burning forests release?

Answer 18

Carbon dioxide

Question 19

How is methane released?

Answer 19

-In agriculture e.g. Growing rice in flooded paddy fields
-And when cattle such as cows pass wind

Question 19

What happens as the amount of methane in the atmosphere increases?

Answer 19

The temperature of the atmosphere is rising as more of the energy from the sun is trapped.

Question 20

What are the effects of climate change?

Answer 20

-Rising temperatures will increase melting of the polar ice sheets and glaciers which will lead to increased sea levels which could lead to more flooding of low-lying areas.
-More severe weather.
-Could change the distribution of animals such as insects and the insect-borne diseases such as malaria.

Question 21

Why do many scientists believe that climate change is caused by human activity?

Answer 21

Because the evidence for climate change is shared between many different scientists and these scientists can criticise the evidence and decide whether it is valid. They can also go through peer-review which can allow scientists to detect false claims e.g. based on poor evidence or bias.

Question 22

Why is there a problem with our understanding of climate change?

Answer 22

-Its complex and difficult to model as sometimes we see stories about climate change in the media that are simplified or simply biased.
-We also see speculation based on only parts of the evidence that means scientises must work harder to communicate the ides around climate change to the general public.
-There are also some uncertainties such as we cannot predict with certainty how much the temperature of the atmosphere will increase which can lead to speculation in the media.

Question 23

What is it meant by the term Carbon Footprint?

Answer 23

It is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.

Question 24

How can we reduce carbon dioxide emissions?

Answer 24

By insulating our homes or turning down the heating.
By using public transport.
By switching to renewable sources of electricity.
By switching to energy-saving lightbulbs.

Question 25

What are the problems of the ways people can reduce carbon dioxide emissions?

Answer 25

Most of the solutions are expensive and people are reluctant to pay.
In some cases they are inconvenient.

Question 26

How can we reduce Methane emissions?

Answer 26

For people to eat less beef and less dairy products.
In Landfills we can trap the methane and burning it to produce electricity.

Question 27

What are the problems of the ways people can reduce methane emissions?

Answer 27

People enjoy eating beef and dairy products and are unlikely to change their diets.
Trapping and burning methane costs money.

Question 28

What is it meant by a fuel?

Answer 28

Fuels release energy when they are combusted (burned).

Question 29

What are two examples of fuels?

Answer 29

-Coal
-Hydrocarbons

Question 30

What do we need for complete combustion to happen?

Answer 30

We need plenty of oxygen.

Question 31

What is carbon monoxide?

Answer 31

A toxic gas which has no colour and no smell.

Question 32

How is Sulfur dioxide produced?

Answer 32

Since coal contains the element sulfur, when coal is burned the sulfur atoms are oxidised which produces the gas sulfur dioxide.

Question 33

How is Oxides of nitrogen produced?

Answer 33

Oxides of nitrogen are produced inside engines and here high temperatures cause nitrogen and oxygen from the air to react which produces a range of different molecules so scientists call them oxide of nitrogen (NOx)

Question 34

How do Oxides of nitrogen and Sulfur dioxide cause problems for humans?

Answer 34

They can cause breathing problems in humans.
They also dissolve in rain water to form acid rain which can damage trees and corrode building made from limestone.

Question 35

What are particulates?

Answer 35

Particles of carbon (Soot) and unburned hydrocarbons.

Question 36

How do particulates cause problems for humans?

Answer 36

They can damage human health e.g. they increase the risk of heart disease and lung disease.
They can also reduce the amount of energy from the sun that reaches the Earths surface which is called global dimming.

Question 37

What is possible that global dimming is affecting?

Answer 37

Rainfall patterns