T8:The chemistry of the atmosphere

What are the proportions of gases in the atmosphere today

• 80% nitrogen

• 20% oxygen

Why is evidence for the Earth’s early atmosphere limited?

The evidence for Earth’s early atmopshere is limited beacuse of the time scae of 4.6 billion years.

How did volcanoes form the Earth’s early atmosphere?

• Volcanoes erupted releasing gases to form the early atmosphere

Which two planets would Earth’s early atmosphere have been similair to today?

Mars amd Venus.

What did Earth’s early atmosphere consist of?

Earth’s early atqmosphere consisted of mainly carbon dioxide with little or no oxygen gas.

What gases may volcanoes have produced?

Volcanoes also produced nitrogen which gradually built up in the atmosphere and there may have been small proportions of methane and ammonia.

How did the oceans form?

Water vapour condensed to form the oceans.

What happened when the oceans formed?

When the oceans formed carbon dioxide dissolved in the water and carbonates were precipitated producing sediments, reducing the amount of carbon dioxide in the atmosphere.

How did oxygen increase in Earth’s early atmosphere?

The first simple organisms such as algae and green plants photosynthesised by absorbing carbon dioxide and releasing oxygen back into the atmosphere.

When did algae first produce oxygen?

2.7 billion years ago.

What is the equation for photosynthesis?

In what 2 ways did the percetages of carbon dioxide in Earth’s early atmosphere decrease?

• Algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis.

• Carbon dioxide was also decreased by the formation of sedimentary rocks and fossil fuels that contain carbon.

How was Limestone formed?

Limestone was made from the calcium carbonate deposits fro the shells and skletons of marine organisms.

How was coal formed?

From thick plant deposits.

How was oil and natural gas formed?

From deposits of plankton.

What do greenhouse gases in the atmosphere help to do?

Greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life.

Name 3 greenhouse gases:

• Water vapour

• Carbon dioxide

• Methane

How does the greenhouse effect work?

• The sun emits shortwave radiation

• Most of this radiation passes through the Earth's atmosphere and reaches the surface. 

• The Earth's surface absorbs this radiation and warms up. It then re-emits the energy as longwave radiation, primarily infrared radiation. 

• Greenhouse gases in the atmosphere absorb a portion of this outgoing infrared radiation. 

• The absorbed radiation heats the atmosphere, which in turn radiates heat back towards the Earth's surface. 

What are 4 human activities that increase the amount of greenhouse gases in the atmosphere?

• Deforestation

• Burning fossil feuls

• Agricultural farming

• Landfill sites

What do many scientists believe about the temperature of the Earth’s atmosphere?

Many scientists believe that human activities will cause the temperature of the Earth’s atmosphere to increase at the surface and that this will result in global climate change

Climate change is a very complex thing to model and that is why it leads to……….

Simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased.

What is a major cause for climate change?

An increase in average global temperature

What are 4 possible effects of global climate change?

• An increase in tempearure could lead to the polar ice caps melting causing a rise in sea levels ,increasing flooding in coastal areas and coastal erosion

• Changes in rainfall patternsmay cause some regions to get too much or too little water affecting the ability of certain regions to produce food.

• The frequency and serverity of storms may increase.

• Changes in the temperature and amount of water available may affect wild species,leading to differences in their distribution.

What is carbon footprint?

The carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.

How can carbon footprint be reduced?

The carbon footprint can be reduced by reducing emissions of carbon dioxide and methane.

What are 2 actions which could reduce the emissions of carbon dioxide and methane into the atmosphere?

• Using renewable energy sources instead of fossil feuls.

• Governments could tax companies based on the amount of carbon dioxide they emit.

Give two reasons why action from governments could be limited to reduce carbon footprint;

• A lot of money may be needed to invest into alternative technologies that lower carbon dioxide emissions

• People may be reluctant to make changes to their lifestyle.

What is a major sourceof atmospheric pollutants?

The combustion of fossil fuels.

What do most fuels ,including coal, contain?

• Carbon

• hydrogen

• sulfur.

What gases are released into the atmosphere when a fuel is burned?

• carbon dioxide

• water vapour

• carbon monoxide

• sulfur dioxide

• oxides of nitrogen.

What might solid particles and hydrocarbons be released into the atmosphere in the form of?

Particles.

How is carbon monoxide and soot produced by burning fuels?

• Carbon monoxide is produced

• when there isn’t enough oxygen

• so incomplete combustion takes place

• releasing carbon monoxide and soot into the atmosphere.

How are sulfur dioxides produced by burning fuels?

• Sulfur dioxide is released during the

• combustion of fossil fuels

• that contain sulfur impurities

• causing the sulfur to become oxidised

• releasing sulfur dioxides.

How are nitrogen dioxides produced by burning fuels?

• Nitrogen oxides are created from a reaction between the

• nitrogen and oxygen in the air

• caused by the heat of burning.

What is carbon monoxide and what is its properties?

• Carbon monoxide is a toxic gas.

• It is colourless and odourless and so is not easily detected.

What can carbon monoxide do that makes it so dangerous?

• Carbon monoxide is dangerous because

• it can stop the blood from carrying oxygen around the body

• by binding to the haemoglobin in your red blood cells

• that normally carry oxygen so less oxygen can be carried around your body.

• This can lead to fainting, a coma or death.

What does sulfur dioxide and oxides of nitrogen cause ?

Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain.

what do particulates in the atmosphere cause?

Particulates cause global dimming and health problems for humans.

How do particulates cause respiratory problems?

• If particulates are inhaled

• they chang get stuck in the lungs

• and cause damage

• which causes respiratory problems.

How do particulates cause global dimming?

• Particulates or the clouds they help produce

• reflect sunlight back into space

• so less light reaches the Earth

• which causes global dimming