Chemistry of the Atmosphere Flashcards
Paper 2 - C9
What are the % for the gases in the atmosphere of the Earth today?
Nitrogen - 78%
Oxygen - 21%
Other gases (Carbon dioxide, water vapour, and noble gases such as argon) - 1%
Why can scientists cannot be certain about the early atmosphere?
Because the Earth is 4600 million years old
What do scientists think happened in the first billion years of Earth?
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.
What did the volcanoes produce?
-Nitrogen
-Water Vapour
-Small amounts of methane and ammonia
-Carbon dioxide
What were the gases like in the Earth’s early atmosphere?
Mainly consisted of carbon dioxide with small but increasing amounts of nitrogen.
How did the Earths early atmosphere transform into the atmosphere today?
-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.
How is coal formed?
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.
What happens if the remains of ferns and trees die in marshy wetlands?
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.
How is oil formed?
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.
How is natural gas formed?
We often find natural gas near deposits of oil that is because natural gas is formed from plankton in a similar way to oil.
What does natural gas mainly consists of?
The hydrocarbon methane
What do all fossil fuels contain?
Trapped carbon
What are the main greenhouse gases?
Water vapour
Carbon dioxide
Methane
What is it meant by the greenhouse effect in terms of short and long wavelength radiation?
-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.
Why is the greenhouse effect essential to life on Earth?
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.
Why do we burn coal?
-For electricity.
-Petrol and diesel to power cars.
-Gas to heat our homes.
Why is deforestation happening?
To provide land for grazing cattle
What does burning forests release?
Carbon dioxide
How is methane released?
-In agriculture e.g. Growing rice in flooded paddy fields
-And when cattle such as cows pass wind
What happens as the amount of methane in the atmosphere increases?
The temperature of the atmosphere is rising as more of the energy from the sun is trapped.
What are the effects of climate change?
-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.
Why do many scientists believe that climate change is caused by human activity?
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.
Why is there a problem with our understanding of climate change?
-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.
What is it meant by the term Carbon Footprint?
It is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
