Combined Chemistry - C9 Chemistry of the atmosphere Flashcards
For approximately how many years have the proportion of gases in the atmosphere stayed the same?
200 million years
What are the approximate proportions of nitrogen and oxygen in our atmosphere (as a fraction and percentage).
- Nitrogen (4/5 or 80%)
- Oxygen (1/5 or 20%)
Other than Nitrogen and Oxygen, name some gases that are present in very small quantities in our atmosphere.
- Water vapour
- Noble gases
- Carbon dioxide
Why is there only limited evidence of what the early atmosphere was like and how it evolved?
Because there is such a large timescale (4.6 billion years).
One theory suggest that the Earth’s early atmosphere was shaped by intense volcanic activity.
a) Name the planets that have similar atmospheric conditions to those described by this theory.
b) What was the main gas present in the atmosphere at this time?
a) Mars and Venus
b) Carbon dioxide
How do most scientists believe the oceans were formed?
Water vapour in the early atmosphere condensed to form the oceans
Describe the composition of gases in the early atmosphere.
- Mainly carbon dioxide
- With small amounts of methane and ammonia
How did the amount of carbon dioxide in the early atmosphere reduce?
- Dissolved in the oceans
- Locked up in sedimentary rocks (carbonate precipitate forming sediment)
- Locked up in fossil fuels (calcium carbonate shells of marine organisms)
Write a word and balanced symbol equation for photosynthesis.
carbon dioxide + water → glucose + oxygen
6CO2 + 6H2O → C6H12O6 + 6O2
Describe how the oxygen levels in the early atmosphere increased?
- Algae produced oxygen by photosynthesis 2.7 billion years ago.
- Over the next billion years, plants evolved and produced oxygen by photosynthesis.
As well as increasing oxygen levels, what other effect did algae and plants have on the atmosphere?
Reduced carbon dioxide in the atmosphere (by photosynthesising)
Describe how limestone is formed
- Dead marine organisms fall to the bottom of the sea.
- Their calcium carbonate shells and skeletons are compressed over millions of years.
- Calcium carbonate rock (limestone) is formed. This is a sedimentary rock.
Describe how coal is formed.
- Plant deposits fall to the bottom of the sea.
- The plant deposits are covered by layers of sediment.
- Over millions of years, the plant deposits are compressed and coal is formed.
Describe how crude oil is formed.
- Deposits of dead plankton collect at the bottom of the sea.
- They become buried by layers of sediment and are compressed over millions of years.
- Crude oil and natural gas are then formed and are found as resevoirs deep underground.
Describe how natural gas is formed.
- Deposits of dead plankton collect at the bottom of the sea.
- They become buried by layers of sediment and are compressed over millions of years.
- Crude oil and natural gas are then formed and are found as resevoirs deep underground.
Name the three main greenhouse gases.
- Water vapour
- Carbon dioxide
- Methane
Explain what is meant by the ‘Greenhouse Effect’.
- The Greenhouse Effect is the warming of the Earth’s surface due to greenhouse gases.
- The greenhouse gases don’t absorb the short wave radiation from the sun
- However, they do absorb the long wavelength radiation that is reflected off the Earth’s surface.
- They then re-radiate this long-wavelength radiation, some of which travels back towards Earth - giving a warming effect.
Suggest two human activities that increase the amount of greenhouse gases (e.g. methane and carbon dioxide).
Any two from:
- Agriculture/Farming (farm animals produce large amounts of methane)
- Creating waste (decomposition produces CO2)
- Deforestation (fewer trees means less CO2 is absorbed through photosynthesis)
- Burning fossil fuels (’locked up’ carbon is released as CO2 is produced)
Do most scientists agree that human activities are causing global climate change?
Yes, evidence for climate change has been peer-reviewed and most scientists believe human activities will cause the Earth’s temperature at the surface to rise.
What are the issues with the way in which the media portrays global climate change?
The media portrays simplified models, speculation and opinions which may lead to bias.
List three consequences of climate change.
Any three from:
- Sea levels rising
- Increased flooding in coastal areas
- Increased frequency of droughts
- Changes in rainfall patterns
- Increase in frequency and severity of extreme weather events (e.g. storms)
- Changes in distribution of wild animals and plants
What is meant by ‘carbon footprint’?
The total amount of carbon dioxide and other greenhouse gases emitted over the full lifecycle of a product, service or event.
Suggest three ways to reduce your carbon footprint by reducing emissions of carbon dioxide and methane.
Suggestions include:
- Eating more locally sourced food
- Fewer car journeys (e.g. car pooling or walking/cycling instead)
- Using renewable energy to power your home
- Producing less waste (e.g. buying products with less packaging)
- Reusing or Recycling Products
What is the cause of global dimming?
Solid particulates released from burning fuels
Name the two gases that cause acid rain
- Sulfur dioxide
- Oxides of Nitrogen
Name the two gases that can be released by burning fuels that cause respiratory problems in humans
- Sulfur dioxide
- Oxides of Nitrogen
Name the toxic, colourless and odourless gas that can be released when burning fuels
Carbon monoxide
What type of combustion often results in carbon monoxide and soot (carbon particles) being released?
Incomplete combustion
If a fuel contains sulfur impurities, what gas will be released during combustion of the fuel.
Sulfur dioxide
