c9: chemistry of the atmosphere

what are the proportions of gas in the atmosphere?

• about 80% nitrogen

• about 20% oxygen

• small proportions of various other gases including carbon dioxide, water vapour and noble gases

explain one theory of the earth’s early atmosphere

there was intense volcanic activity that released gases that formed the early atmosphere and water vapour that condensed to form the oceans

what did the earth’s atmosphere consist of at the start of the early periods?

mainly carbon dioxide with little or no oxygen gas

what did volcanos produce?

nitrogen which gradually built up in the atmosphere and there may have been small proporations of methane and ammonia

what happened when the oceans formed?

carbon dioxide dissolved in the water and carbonate were precipitated producing sediments reducing the amount of carbon dioxide in the atmosphere

how else was carbon dioxide reduced?

algae and plants decreased carbon dioxide in the atmosphere by photosynthesis

state how sedimentary rocks formed.

• carbon dioxide is a very soluble gas

• it dissolves readily in water

• as the oceans formed, carbon dioxide dissolved to form soluble carbonate compounds so its amount in the atmosphere decreased

• carbonate compounds were then precipitated as sedimentary rocks

what does the greenhouse effect involve?

the interaction between short and long wavelength radiation

what does the sun emit?

shortwave radiation that passes through the atmosphere and heats the earth’s surface

what does the earth radiates?

the energy back as long wave infrared radiation

what does the greenhouse in the atmosphere do?

• absorbs some of this out going long wave radiations

• trapping the heat

• reradiating it back to the earth, causing the planet to warm up

state two human activities that increase carbon dioxide.

1. buring fossil fuels for energy

2. deforestation

state two human activities that increase CH4

1. livestock farming

2. the decomposition of waste in landfill

state four potential effects of climate change.

1. more frequent and intense extreme weather event

2. rising seas levels due to emitting glaciers

3. distribution of ecosystems and biodiversity

4. negative impacts on human health and food security

define carbon footprint.

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

state three ways to reduce carbon dioxide and methane emission.

1. shift to renewable energy sources

2. improve energy efficient in homes and transportation

3. adopting sustainable food and waste management