chemistry topic 9 Flashcards
what gasses and in what percentages make up the earths atmosphere
80% N2
20% O2
<1% CO2, H2O + Noble Gases
why is Evidence for the early atmosphere of the earth limited
because of the time scale of 4.6
billion years.
how has earths atmosphere changed over time
carbon dioxide has decreased:
* dissolved in oceans forms hydrogen carbonates
* ‘locked up’ in sedimentary rocks - forms carbonates
* Taken up by plants during photosynthesis
oxygen has increased because:
* released by plants during photosynthesis
nitrogen has increased because:
* methane/ ammonia reacted with oxygen
* nitrogen is released by bacteria and in decay
* nitrogen builds up due to being unreactive
how where oceans formed
volcanic activity released water vapour, nitrogen and CO2. Water vapour condensed to form oceans
when did algae first produce oxygen
about 2.7 billion years ago.
how is Gas + Oil formed
plankton/tiny marine organisms died Got buried
and subjected to high temperature and pressure over millions of years
how is coal produced
Plants / trees absorb carbon dioxide
Plants / trees release oxygen
Plants “trap” carbon when growing
When they die and get buried, turns to coal
what increases carbon dioxide
Burning fossil fuels and
deforestation
what increases methane
Farming of livestock and landfills
how can we be sure that climate change exists
Peer-reviewed evidence shows the temperature of the Earth is increasing resulting in climate change.
why is global climate change difficult to model
Global climate change is difficult to model as it is a complex system. This leads to simplified models, speculation and opinions which may be biased.
what are the three greenhosue gasses
- Carbon dioxide
- Water vapour
- Methane
what do greenhouse gasses do
Greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life.
what leads to global warming
Earth absorbs short wavelength radiation, reradiates it at long wavelength radiation. These are reflected back to Earth heating it up
what does climate change lead to
Rising sea levels causing flooding
Droughts
Ice caps melting
what is the carbon footprint
The carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of the product, service or event.
can can your carbon footprint be reduced
Can be reduced by reducing carbon dioxide and methane emissions
what does an Incomplete combustion (lack of oxygen) release
- carbon monoxide - colourless, odourless, toxic – leads to respiratory problem
- soot - carbon particles leads to global dimming
what does Complete combustion release
- Carbon dioxide – leads to global warming
what chemicals are found in fules
Sulfur and nitrogen
what do the chemicals found in flues lead to
sulfur dioxide and oxides of nitrogen – leads to acid rain and respiratory problems
how are nitrogen oxides formed
Nitrogen oxides are formed from car engines at high temperatures
what do scrubbers do
Scrubbers in power plants can remove SO2/NOx from fumes
