Chemistri of the Atmosphere Flashcards
(24 cards)
What did the early atmosphere contain ?
a large amount of carbon dioxide
little or no oxygen
small amounts of other gases, such as ammonia and methane
Where did the atmosphere come from?
One theory suggests that the early atmosphere came from intense volcanic activity, which released gases that made the early atmosphere very similar to the atmospheres of Mars and Venus today.
How was water formed in the early atmosphere
Volcanic activity also released water vapour, which condensed as the ocean
How was nitrogen released into the early atmosphere ?
Nitrogen was probably also released by volcanoes which gradually built up in the atmosphere because it is unreactive.
How oxygen increased ?
Perfect answer….
Photosynthesis by primitive plants and algae released oxygen, which gradually built up in the atmosphere. Eventually, the amount of oxygen present in the atmosphere enabled animals to evolve.
carbon dioxide + water → glucose + oxygen
Photosynthesis takes in carbon dioxide and releases oxygen decreasing CO2 level and increasing O2 levels.
How CO2 decreased ?
Limestones
Carbon dioxide is a very soluble gas. It dissolves readily in water. As the oceans formed, carbon dioxide dissolved to form soluble carbonate compounds so its amount in the atmosphere decreased. Carbonate compounds were then precipitated as sedimentary rocks, eg limestone.
Greenhouse gases present in the atmosphere include:
water vapour
carbon dioxide
methane
What do greenhouse gases do ?
absorb heat radiated from the Earth
then release energy in all directions, which keeps the Earth warm
How greenhouse effect works ?
1) Electromagnetic radiation at most wavelengths passes through the Earth’s atmosphere.
2) The Earth absorbs most of the radiation and warms up.
3) The Earth radiates energy as infrared radiation.
4) Some of the infrared radiation goes into space.
5) Some of the infrared radiation is absorbed by greenhouse gases in the atmosphere.
6) The lower atmosphere warms up.
Human activities are increasing the amount of some greenhouse gases in the atmosphere.
For example:
1) farming cattle releases methane
2) farming rice in paddy fields releases methane
3) burning fossil fuels in vehicles and power stations
releases carbon dioxide
4) deforestation releases carbon dioxide and reduces
the absorption of carbon dioxide through
photosynthesis
Is climate science predictable ?
However, climate science is complicated and it is difficult to predict and explain what will happen to global temperatures in the future, so scientists cannot be certain about global warming.
When evaluating the quality of evidence on an issue like global warming, you should consider:
1) who did the research and whether they are trustworthy, skilled and experienced
2) who funded the research, because that might cause some bias
3) what methods were used to collect and analyse the data, because that might cause uncertainties in the evidence base
4) which organisation is reporting or publishing the evidence
Weather
The day-to-day condition of the atmosphere.
Climate Change
Average weather conditions over longer periods and over large areas.
Global Warming
The rise in the average temperature of the Earth’s surface.
The effects of global warming include:
- glaciers and polar ice melting
- sea levels rising
- patterns of rainfall changing, producing floods or droughts
- habitats changing
Suggest and explain three ways that someone living in the UK could reduce their carbon footprint.
- Fit photovoltaic solar panels onto the roof of their house, which will reduce the amount of electricity they use which has been generated from fossil fuels.
- Commute to work by bicycle instead of driving.
- Improve their home insulation (eg loft insulation or double glazing) which will reduce the amount of gas burned in the boiler.
Carbon Footprint
A measure of how much carbon is used through the activities of a person, company or country.
Complete combustion
Complete combustion of a hydrocarbon fuel occurs when there is a good supply of oxygen. It releases the maximum amount of energy and produces carbon dioxide and water.
Complete combustion equation
methane + oxygen → carbon dioxide + water
CO2 and H2O always products
Incomplete combustion
Incomplete combustion of a hydrocarbon fuel occurs when there is a poor supply of oxygen. Less energy is released. Water is still produced from the hydrogen atoms. Instead of carbon dioxide, you might get carbon monoxide or particulate carbon, known commonly as soot, or a mixture of both.
Incomplete combustion equation
ethane + oxygen → carbon monoxide + water
H2O still present but no CO2
Carbon monoxide risks
Carbon monoxide is a poisonous gas which binds to haemoglobin in your red blood cells, preventing them from carrying oxygen to the cells in your body. Carbon monoxide is colourless and has no smell, so it is very difficult to tell if you are breathing it in. It can be detected by electronic detectors which are often fitted near to boilers.
Particulate carbon
Particulate carbon can cause health problems for humans because it irritates the lining of the lungs, can make asthma worse, and perhaps even cause cancer. Particulate carbon can also cause global dimming, which may reduce rainfall.
