C13 Flashcards
how many years ago was the earth formed
4.6 billion
how do scientists know about the atmosphere from the past
using evidence from gas bubbles trapped in ancient rocks and data from atmospheres of other plantes
what did volcanoes release that formed the early atmosphere
carbon dioxide, water vapour and nitrogen
how did water come to earth
water vapour condensed as the earth cooled and fell as rain
icy comets rained down on the earths surface and melted bringing water to earth
how were oceans formed
water collected in hollows in the crust as the rock solidified and formed oceans
when did life on earth begin
3.4 billion years ago
what were the first life forms on earth
simple organisms like bacteria. They used the breakdown of chemicals as a form of energy
when did bacteria and algae evolve
2.7 billion years ago
how was oxygen originally produced on earth
algae started photosynthesising to produce its own food and produced oxygen as a waste product
how did oxygen become so prominent in the atmosphere
more plants evolved which produced more oxygen and removed carbon dioxide
how does carbon end up in the skeletons and skulls of animals
carbon in glucose is released during photosynthesis and can end up in plant material which is then eaten by animals and some of the carbon transfers into their skeletons which then form sedimentary carbonate rocks
how are sedimentary carbonate rocks formed
when skeletons at the bottom of the ocean become covered in sediment and form rocks under pressure
how were fossil fuels formed
some animal and plant remains were crushed by large scale earth movements and heated in the earths crust forming coal, oil and gas
how was coal formed
formed from thick deposits of plant material that died in swamps, were buried in the absence of oxygen and compressed
how were oil and natural gas formed
from plankton remains deposited in muds on the seabed. remains were covered in sediment that became layers of rock when compressed over millions of years. crude oil and natural gas are trapped beneath these layers of rock
how long have the proportions of gases in the earths atmosphere been similar
200 million years
what are greenhouse gases and what are the main ones
greenhouse gases are gases that absorb energy radiated from it’s surface. The main ones are carbon dioxide, methane and water vapour
how do greenhouse gases cause global warming
they absorb infrared radiation which stimulates the bonds in the molecules to bend, vibrate and stretch, raising their temperature (global warming)
what is the carbon footprint of a product, service or event
total amount of co2 and other greenhouse gases emitted over it’s full life cycle
what are 2 problems of trying to reduce global carbon footprint
restrictions could hinder poorer countries’ development as they are yet to industrialise
reductions have cost implications in manufacturing and transport industries
what happens with sulphur in fossil fuels
reacts with oxygen when burned and forms sulphur dioxide. This causes acid rain which damages trees, kills aquatic animals and plants and attacks limestone buildings
what happens when there is not enough oxygen in an engine
incomplete combustion occurs so co2 and co is formed. Carbon monoxide is a toxic gas that can kill humans
what does high temperature in an engine cause
the normally unreactive nitrogen gas in the air reacts with oxygen making nitrogen oxide which can cause acid rain and trigger asthma
how do diesel engines cause global dimming
they burn hydrocarbons with bugger molecules than petrol engines. When these molecules react with oxygen they don’t burn completely. The particles produced travel into the upper atmosphere reflecting sunlight into space which causes global dimming
