[C9] Chemistry of the atmosphere

What percentage of the atmosphere is nitrogen gas?

About 80%

What percentage of the atmosphere is oxygen gas?

About 20%

What percentage of the atmosphere is carbon dioxide, water vapour and noble gases?

Small amounts

Describe the atmosphere of the early Earth

Initally the atmopshere consisted mainly of carbon dioxide with little or no oxygen gas. Nitrogen was then produced in volcanic eruptions and built up in the atmosphere. There may have been small amounts of methane and ammonia

How has the amount of oxygen in the atmosphere changed from the early atmosphere to today?

Increased

How has the amount of carbon dioxide in the atmosphere changed from the early atmosphere to today?

Decreased

How has the amount of nitrogen in the atmosphere changed from the early atmosphere to today?

Decreased

How old is the Earth?

4.6 billion years old

How did the amount of carbon dioxde in the atmosphere decrease?

- Dissolved in the oceans - Formed carboante compounds in oceans (which were either precipitated as sedimentary rock or used by marine animals to make shells) - Used by plants in photosynthesis - 'Locked up' in rocks and fossil fuels when organisms die

Why did lots of carbon dioxide dissolve in the oceans?

It is very soluble

How were oceans formed?

Water vapour condensed as the Earth cooled and fell as rain. The rain collected to form oceans

How did the amount of oxygen in the atmosphere increase?

Algae evolved and photosynthesised which created oxygen gas

Name three greenhouse gases

carbon dioxide, methane, water vapour

Describe how greenhouse gases insulate the Earth

- short wavelength infrared radiation travels from the sun and is absorbed by the Earth - long wavelength radiation is emitted back from the surface of the Earth - greenhouse gases trap the long wavelength infrared radiation and re-rediate it in all directions including back towards Earth

What type of radiation do greenhouse gases absorb?

long wavelength radiation

How has the global temperature changed in recent decades?

Increased

How has the abundance of greenhouse gases in the atmosphere changed?

Increased

What human activities that release greenhouse gases?

Deforestation. Burning fossil fuels. Agriculture. Creating waste

Describe how deforestation leads to the greenhouse effect

- Trees remove carbon dioxide from the atmosphere through photosynthesis - Carbon dioxide is a greenhouse gas - Fewer trees means less carbon dioxide can be removed

Describe how burning fossil fuels leads to the greenhouse effect

- Burning fossil fules release carbon dioxide into the atmosphere - Carbon dioxide is a greenhouse gas

Describe how agriculture leads to the greenhouse effect

- Farm animals release methane - Methane is a greenhosue gas

Describe how creating waste leads to the greenhouse effect

- Carbon dioxide and methane are released at landfil sites when waste decomposes - Both are greenhouse gases

What is global warming?

The increase in the average temperature of the Earth

What is climate change?

The long term alteration in weather patterns

What is the link between global warming and climate change?

Global warming leads to climate change

Why is the evidence linking gloal warming to climate change reliable?

It is peer reviewed

Why do many people not accept the evidence on climate change?

It is difficult to model complex systems such as global climate change, this has lead to simplfied models, speculation and opinions based on the media

State four effects of climate change

Rising sea levels. More extreme weather conditions (storms and droughts). Changes in the distribution of wildlife. Changes in rainfall patterns and temperatures

What is the carbon footprint?

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

How can the carbon footprint be reduced?

Reduce emissions of carbon dioxide and methane

How could emissions of carbon dioxide and methane be reduced?

- Use renewable energy resources instead of fossil fuels - Recycle more to avoid waste being sent to landfil - Reduce waste

How is carbon monoxide released into the atmosphere?

Incomplete combustion of fossil fuels

What harmful effects does carbon monoxide have?

Prevents red blood cells from carrying oxygen. Leads to death

What are particulates?

Solid particles such as unburnt carbon

Why are particulates harmful?

Cause respiratory problems. Cause global dimming

What is global dimming?

The gradual reduction in radiation reaching the Earth's surface from the sun

How are particulates released into the atmosphere?

Incomplete combustion of fossil fuels

What is soot?

Unburnt carbon

How is sulfur dioxide released into the atmosphere?

Combustion of fossil fuels containing sulfur impurities

What harmful effects does sulfur dioxide cause?

Acid rain. Respiratory problems

How are oxides of nitrogen released into the atmosphere?

The reaction between oxygen and nitrogen caused by the heat of car engines

What harmful effects do oxides of nitrogen cause?

Acid rain. Respiratory problems

Why is carbon monoxide not easily detected?

It is colourless and odourless