Green Chemistry Flashcards
Is water vapour a greenhouse gas?
water is a greenhouse gas) because it absorbs infrared (IR) radiation (1)
The polarity of the water molecule changes when its bonds vibrate
Define greenhouse gas
(A greenhouse gas) traps/absorbs/ reflects IR (radiation) / heat (1)
(re-radiating) from the earth (1)
What does the relative greenhouse factor do?
The relative greenhouse factor compares effect different greenhouse gases have at absorbing infrared radiation compared to CO2.
What is GWP?
GWP (Global Warming Potential) is a measure of how much a given mass of greenhouse gas contributes to global warming. It’s determined by:
• ability to absorb infrared radiation (relative greenhouse factor)
• half-life in atmosphere - a measure of how long they last in the atmosphere before reacting & being broken down
What is IPCC?
IPCC (Internal Panel on Climate Change) gives a possible error of +/- 35% in their figures. Shows how unreliable long-term predictions of climate change are.
What is anthropogenic climate change?
Anthropogenic climate change is climate change caused by actions of human beings, e.g. burning fossil fuels, deforestation etc.
What is natural climate change?
Natural climate change is climate change due to natural processes occurring on Earth, e.g. dissolving of CO2 in sea water & formation of carbonate rocks.
What are the most significant greenhouse gasses?
The most significant greenhouse gases are CO2, CH4 & N2O.
How can a climate record be obtained?
Ice cores removed by drilling deep samples from an ice sheet, e.g. polar icecaps of Antarctica/Greenland. Ice forms from a build-up of layers of snow every year, lower layers are older than upper layers, an ice core contains many years of layers. Properties of the ice/inclusions within the ice can be used to reconstruct a climactic record for the age range of the core.
How can ice cores be used to tell information?
When the temperature falls, water molecules with heavier isotopes condense faster than normal water molecules. Relative concentrations of these in ice cores can be used to reconstruct local temperature changes.
Air bubbles trapped in ice cores let scientists measure atmosphere concentrations of trace gases, such as CO2, CH4 & N2O.
Why does the amount of carbon dioxide is in the atmosphere fluctuate?
About 45% of anthropogenic CO2 emissions remain in the atmosphere, 30% taken up by oceans & the rest taken up by trees & other plants. Of the CO2 that goes into the atmosphere, about 50% is removed over 30 years, 30% more in a few centuries & 20% will stay for many thousands of years.
What is a major cause of anthropogenic climate change?
air traffic. Jet aircraft produce frozen water vapour trails called contrails (water vapour is a greenhouse gas). They’re not officially classed as air pollution but can contribute to long-term changes in Earth’s climate. Jet engines also produce nitrogen oxides which are a greenhouse gas & destroy ozone.
What does carbon neutral mean?
A fuel is carbon neutral if the amount of CO2 absorbed when the raw material was grown/
fuel was formed, is the same as produced when it’s manufactured & burned. E.g. trees are carbon neutral.
What are petroleum fuels? Are they is carbon neutral?
Petroleum fuels were formed millions of years ago, by microorganisms that took CO2 from the atmosphere, and when burned produce CO2. They aren’t carbon neutral as the CO2 produced can’t be set against the CO2 absorbed in a reasonable time span (50 years).
What are biofuels?
Biofuels, e.g. ethanol from maize, aren’t carbon neutral. The stages in production require energy generated by burning fossil fuels so gives out more CO2 than taken in.
