chemistry of the atmosphere
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what does the Earth's atomsphere consist of today give proportions of nitrogen oxygen and other gases
78 percent nitrogen 21 percent oxygen 1 percent other gases such as carbon dioxide water vapour and argon
why can’t sure about the Earth’s early atmosphere
because the Earth formed 4.6 billion years ago
what do scientists believe caused the earth’s early atmosphere
intense volcanic activity volcanoes released gases that formed the atmosphere
volanic activity released gases that formed atmosphere one of these was water vapour explain water vapour
As earth cooled, water vapour condensed to form the oceans. volcanoes also released huge amounts of carbon dioxide
intense volcanic activity released gases that formed Earth’s early atmosphere these gases included water vapour which condensed to form the oceans but volcanoes also released huge amounts of carbon dioxide so at the early stage, what did the earth’s atmosphere consist of
-mainly carbon dioxide with virtually no oxygen
what planets today was the Earth’s early atmosphere similar to
mars and venus
As well as releasing water vapour and huge amounts of carbon dioxide, volcanoes also released nitrogen which built up in the atmosphere what two other small amounts of gases were released by volcanoes:
ammonia and methane
differences between Earth’s early atmosphere and the atmosphere of the Earth today:
Early atmosphere contained large amounts of carbon dioxide but atmosphere today only contains small amounts -early atmosphere contained small amount of nitrogen whereas today 78 percent of the atmosphere is nitrogen Early atmosphere contained very little oxygen whereas today 21 percent of the atmosphere is oxygen
how did these changes in atmosphere happen
• water vapour released from intense volcanic activity condensed to form the oceans as the earth cooled • some of the carbon dioxide dissolved in the oceans to form a weak acid which reacted with minerals in the sea forming precipitates • overtime these precipitates formed sediments of carbonate rock on the seabed
how did carbon dioxide levels decrease
-water vapour released from volcanic activity condensed to form oceans -carbon dioxide dissolved in the sea to form weak acid which reacted with sea minerals to form precipitates over time the precipitates formed sediments of carbonate rock on the sea bed some of the carbon dioxide in the sea was used to make shells of organisms such as mussels and coral when these died they formed sedimentary rock limestone. this removed co2 from the atmosphere
how did oxygen levels increase
around 2.7 billion years ago, photosynthetic algae first evolved in the oceans. photosynthesis produced oxygen which entered the atmosphere. plants began to evolve this increased amount of oxygen in the atmospehere. the level of oxygen reached a point where animals could evolve. photosynthesis takes in carbon dioxide and this carbon dioxide was locked in fossil fuels
fossil fuels list the three fossil fuels
• coal • oil • gas
recap point- the early atmosphere contained large amounts of co2 but virtually no oxygen today the earth’s atmospehere contains plenty of oxygen but small amounts of co2. photosynthesis takes in carbon dioxide and produces oxygen some of that carbon dioxide can be locked into fossil fuels list the three
coal oil gas
fossil fuels formed over millions of years they are non renewable is we keep using them they will…..
run out eventually
how is coal formed
coal is formed from the remains of ferns and trees these die in marshy wetlands and do not decompose due to two factors lack of oxygen and acidic conditions (both those factors prevent bacteria from carrying out decomposition) overtime, the plant remains are covered with sediment and compressed high temperatures and pressures creates coal
how is crude oil formed
crude oil is formed from plankton which are tiny plants and animals found in the sea when plankton die they settle in mud on the seabed if oxygen is not present then they do not decompose overtime they become compressed by sediment heat and pressure converts them into crude oil
how is natural gas formed
natural gases can be hydrocarbons or methane often found near oil deposits that is because natural gas is formed from plankton in a similar way to oil
all fossil fuel contains trapped carbon that carbon was part of carbon dioxide taken in by photosynthesis algae and plants decreased percentage of co2 in the atmosphere by photosynthesis but whta else decreased carbon dioxide levels
carbon dioxide was also decreased by formation of sedimentary rocks and fossil fuels that contain carbon
what are coal and hydrocarbons used for
coal- used to generate electricity hydrocarbon- used to power vehicles such as cars
most fuels including both coal and hydrocarbons contain the elements carbon and hydrogen when we burn these fuels the carbon and hydrogen atoms react with oxygen in the air
the elements are oxidised
methane is found in natural gas and used to heat homes carbon atoms in methane molecules are oxidised to form carbon dioxide what are hydrogen atoms oxidised to form
-water vapour
what is needed for complete combustion to occur
a good supply of oxygen
carbon dioxide is a greenhouse gas . when can carbon dioxide be released
when humans burn fuels this releases carbon dioxide
how does carbon dioxide affect the environment
• its a greenhouse gas - it contributes to climate change