Gases in the Atmosphere

Overview of Gases in the Atmosphere

  • The Earth’s atmosphere is composed of a mixture of gases, primarily nitrogen, oxygen, and argon.
  • Trace gases like carbon dioxide, helium, methane and ozone are present in smaller amounts.
  • The proportions of these gases have remained relatively constant over extended periods of time, however, human activities are beginning to shift this balance.

Composition of the Atmosphere

  • Nitrogen is the most abundant gas, making up approximately 78% of the atmosphere.
  • Oxygen is the second most abundant gas, accounting for about 21% of the atmosphere.
  • Followed by argon, which makes up nearly 1%, and carbon dioxide at roughly 0.04%.
  • The remaining gases (neon, helium, methane, krypton, ozone, amongst others) account for less than 0.01%.

Importance of Gases in the Atmosphere

  • Oxygen is essential for the process of respiration in animals and most types of combustion.
  • Nitrogen is used by plants to make proteins and DNA. It also acts as a diluent for oxygen, preventing rapid and uncontrolled combustion.
  • Carbon dioxide plays a critical role in photosynthesis, a process used by plants and certain organisms to convert light energy into chemical energy.
  • Ozone forms a layer in the high atmosphere which absorbs and scatters the solar ultraviolet radiation.

Global Warming and the Greenhouse Effect

  • Greenhouse gases in the atmosphere, such as carbon dioxide, methane and nitrous oxides, trap heat from the sun, leading to a warming of the Earth, known as the greenhouse effect.
  • This effect is necessary for life as it keeps the Earth’s temperature within life-supporting boundaries.
  • However, an increase in the concentration of these gases, particularly carbon dioxide, due to human activities like burning fossil fuels and deforestation, is causing the Earth’s temperature to rise at a rate faster than normal - this is referred to as global warming.

Air Pollution

  • Human activities also lead to the release of several pollutants into the atmosphere.
  • Sulphur dioxide and nitrogen oxides can react with water in the atmosphere to form acid rain, which is harmful to buildings, statues made of certain materials and ecosystems.
  • Carbon monoxide, a poisonous gas, is produced by incomplete combustion of carbon-containing fuels.
  • The burning of fossil fuels can also produce particulates which contribute to haze and health problems.

The Ozone Layer and CFCs

  • The ozone layer in the upper atmosphere protects living organisms on Earth by absorbing harmful ultraviolet radiation from the sun. However, the ozone layer is being depleted by human-made chemicals, particularly chlorofluorocarbons (CFCs).
  • CFCs were historically used in applications like aerosol propellants, refrigeration and air-conditioning systems. When released into the atmosphere, they can break down and release chlorine atoms, which catalyse the destruction of ozone.

Understanding the gases present in our atmosphere, their percentages and roles, as well as the environmental problems like air pollution, global warming and ozone depletion are crucial for both chemistry and environmental science studies. Remember the importance of reducing our carbon footprint and finding alternatives to harmful substances to prevent further damage to our planet.