chemistry
the earths early atmosphere was thought to contain
- little or no oxygen
- a large amount of carbon dioxide
- water vapour
- small amounts of other gases
explain how condensation of water vapour formed oceans
About 4 billion years ago, the Earth cooled down. This caused water vapour in the atmosphere to condense to liquid water and fell as rain to form the oceans.
explain how the amount of carbon dioxide in the atmosphere was decreased when carbon dioxide dissolved as the oceans formed
Once CO2 was in the water, it reacter to form carbon compounds. The compounds trapped the co2 in the ocean rather then it staying the air. Over time, corals and shellfish used the compounds to build their shells. When their shells died, they turned into limestone which trapped the carbon for millions of years
explain how the growth of primitive plants used carbon dioxide and released oxygen by photosynthesis and consequently the amount of oxygen in the atmosphere gradually increased
Photosynthesis uses carbon dioxide and produces oxygen as a by product. As a result the increasing growth of primitive plants meant that the amount of oxygen in the atmosphere gradually increased.
desribe the composition of todays atmosphere
Nitrogen – about 78% of the atmosphere. Oxygen – about 21% Argon – about 1%
describe the chemical test for oxygen
The test for oxygen is that a glowing splint relights when introduced to a test tube of oxygen
describe the test for carbon dioxide
When carbon dioxide is passed through limewater, the limwater turns milky.
understand what is meant by the term carbon footprint
A carbon footprint is the total amount of greenhouse gases that are generated by our actions
describe the potential effects on the climate of increased levels of co2 and methanane generated by human activity, including burning fossil fuels and livestock farming
food shortages - changes in tempersture and rainfall affect farming, leading to crop failures.
health problems - more heatwaves and air pollution cause breathing issues and heat-related illnesses.
water shortages- droughts make it harder to get clean drinking water
desruibe the major sources of carbon monoxide and particulates and know the problems that the substances can cause
The greatest sources are cars, trucks and other vehicles or machinery that burn fossil fuels.
particulates cause:
nonfatal heart attacks.
irregular heartbeat
carbon monoxide causes:
headache, dizziness, weakness,
udnerstand what is meant by the term acid rain
Acid rain is rainwater that has been made too acidic by some types of air pollution
what substances cause acid rain
sulfur dioxide and nitrogen
explain the problems caused by increased amounts of nitrogen
impair our ability to breathe, limit visibility and alter plant growth.
explain the problems caused by increased amounts of sulfur dioxide
harm the human respiratory system and make breathing difficult
explain the importance of scientists in helping to resolve the problems of acid rain
Scientists help by finding its causes, reducing pollution and restoring the environment. They develop cleaner energy solutions, advise governments on laws and teach people to help.