Chemistry of the Atmosphere

• how long have the proportions of the gases in the atmosphere been like today

  200 million years
• what are the gases found in today's atmosphere

  oxygen, nitrogen, carbon dioxide, water vapour and noble gases
• what are the percentages of the gases in today's atmosphere

  80% nitrogen, 20% oxygen, small amounts of other gases including carbon dioxide, water vapour and noble gases
• what timescale is evidence for the early atmosphere limited to

  4.6 billion years ago
• what theory is given for the earth's early atmosphere

  first billion years intense volcanic activity released gases and water vapour condensed to form oceans.
• what planets is the earth's early atmosphere suggested to be like

  Mars and Venus, consisting mainly of carbon dioxide and little or no oxygen
• what other gas was released by volcanoes

  nitrogen and small proportions of methane and ammonia
• how did the percentage of carbon dioxide reduce in the early atmosphere

  dissolved into the oceans and carbonates precipitated producing sediments
• Why did the percentage of oxygen increase in the early atmosphere

  algae and plants by photosynthesis
• what is the word equation for photosynthesis

  carbon dioxide + water --> glucose + oxygen
• what is the balanced symbol equation for photosynthesis

  6CO2 + 6H2O --> C6H12O6 + 6O2
• when did algae first appear

  2.7 billion years ago
• what did the increase in oxygen from algae and plants lead to

  enables animals to evolve
• why did the percentage of carbon dioxide decrease in the early atmosphere

  algae and plants took it in via photosynthesis, formation of sedimentary rock and in fossil fuels
• what useful substances have been formed as carbon dioxide decreased

  limestone, coal, crude oil and natural gas
• what type of gas maintains the temperature on earth to be high enough to support life

  greenhouse gas
• examples of greenhouse gases are

  water vapour, carbon dioxide and methane
• what is the greenhouse effect on radiation

  absorb heat radiation from the earth then release energy in all directions, which keeps earth warm
• what greenhouse gases are increased due to human activity

  carbon dioxide and methane
• what human activities are increasing the level of carbon dioxide and methane

  farming cattle and rice paddy fields releases methane, burning fossil fuels releases carbon dioxide, deforestation reduces carbon dioxide taken in by photosynthesis
• what do scientists believe human activity will do to the temperature of the earth

  increase it, leading to climate change
• what is the temperature of the earth increasing normally referred to as

  global warming
• what is causing climate change

  increase in average global temperature
• what are the main four potential effects of global climate change

  glacier and polar ice melting, sea levels rising, patterns in rainfall changing leading to floods or droughts, habitats changing
• what is a carbon footprint

  the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event
• how can a carbon footprint be reduced

  by reducing emissions of carbon dioxide and methane
• how can we reduce the emissions of carbon dioxide and methane

  can be difficult e.g. includes reduce use of cars, install solar panels in your home
• what is a major source of atmospheric pollutants

  combustion of fuels
• what do most fuels contain

  carbon, hydrogen and some contain sulphur
• what gases can be released into the atmosphere when a fuel is burnt

  carbon dioxide, water vapour, carbon monoxide, sulphur dioxide and oxides of nitrogen.
• what particles can be released into the atmosphere and what can they lead to

  particulates leading to global dimming
• why are oxides of nitrogen produced when burning a fuel

  high temperature in car engine causes oxygen and nitrogen in air to react

  N2 + O2 --> 2NO
• why is sulphur dioxide produced when burning a fuel

  fuels contain sulphur as an impurity, when the fuel is burnt the sulphur reacts with oxygen to form sulphur dioxide
• what do oxides of nitrogen and sulphur dioxide lead to

  respiratory problems and acid rain
• what does carbon dioxide contribute to and why

  global warming as is a greenhouse gas
• what are the issues with the production of carbon monoxide

  is a toxic gas, prevents blood from carrying oxygen to your cells for respiration
• why is it hard to detect if carbon monoxide is formed

  is odorlous and colourless so can't be seen