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Flashcards in C1g Deck (15):
1

What are the stages of the evolution of the atmosphere?

-volcanoes gave out steam and CO2
-green plants evolved and produced oxygen
-ozone layer allowed evolution of complex animals

2

What happened in phase 1 of the evolution of the atmosphere?

1-Earth surface originally molten, any atmosphere boiled away
2-it cooled and thin crust formed, volcanoes kept erupting, releasing gases from inside the earth. Degassing released mainly CO2, but also steam and ammonia
-atmosphere mostly CO2 and water vapour
-water vapour condensed to form oceans
-very little oxygen

3

What happened in phase 2 of the evolution of the atmosphere?

-lots of CO2 dissolved into oceans
-green plants evolved almost everywhere and photosythesised, removing CO2 and producing O2
-O2 gradually built up and CO2 locked up in fossil fuels and sedimentary rocks
-N2 put in atmosphere by ammonia reacting with oxygen and released form denitryfying bacteria
-N2 is not very reactive so the amount in the atmosphere increased

4

What happened in phase 3 of the evolution of the atmosphere?

-buildup of oxygen killed early organisms that couldn't tolerate it
-allowing evolution of complex organisms that make use of oxygen
-oxygen created the ozone layer (O3), blocking harmful UV rays and enabling even more complex organisms to evolve
-virtually no CO2 left

5

What does today's atmosphere contain?

-78% nitrogen
-21% oxygen
-0.035% carbon dioxide
-varying amounts of water vapour
-noble gases (mainly argon)

6

What processes in the carbon cycle remove oxygen and release carbon dioxide?

-respiration
-combustion
-decay

7

What processes in the carbon cycle remove carbon dioxide and release oxygen?

-photosyntehsis

8

How has human activity affected the composition of air?

-more people and developing countries, more energy needed, more fuel burnt, more pollutants released
-more people=more land to grow food and build houses, deforestation to make space, less plants, less photosynthesis, less carbon dioxide taken out of the atmposphere

9

What do catalytic converters do?

-are one motor vehicles to reduce amount of carbon monoxide and nitrogen oxides getting in the atmosphere
-made of mixture of platinum and rhodium

10

What is photochemical smog, how it it caused, and what effects does it have?

-caused by sunlight reacting with nitrogen oxides
-oxides combine with oxygen to produce ozone (O3)
-breathing difficulties, headaches and tiredness

11

How does carbon monoxide get into the atmosphere?

-formed when petrol or diesel in car engines burns without enough oxygen, incomplete combustion

12

How is acid rain caused?

-burning fossil fuels also releases sulfur dioxide and nitrogen oxides
-when the gases mix with the clouds they form dilute sulphuric and nitric acid
-this falls as rain
-main cause:power stations and internal combustion engines

13

What does acid rain cause?

-causes lake to become acidic and may plants and animals die
-kills trees and erodes limestone buildings and stone statues
-makes metal corrode

14

Where does sulfur dioxide come from?

-sulfur impurities in fossil fuels

15

Where does nitrogen oxides come from?

-a reaction between oxygen and nitrogen in air, caused by the heat of burning
-happens in car engines