9-chemistry Of The Atmosphere

Question 1

Composition of the atmosphere-now

Answer 1

80%-nitrogen
20%-oxygen
0.5%-carbon dioxide, some noble gases water vapour, methane

Question 2

How long has the compositionof the atmopshere been relatively the same

Answer 2

Approx 20. Mill

Question 3

Why are theories and evidence limited

Answer 3

-time scale 4.6bn y

Question 4

What happened in the first billion years

Answer 4

• intense volcanic activity
• released gases- forming early atmosphere
• similar atmosphere to mars and venus- mainly o2 and little to no 02
• water vapour condensed into oceans

Question 5

Composition of the atmosphere-first bn y

Answer 5

• mainly co2 and little to no 02

- nitrogen (increasing amounts), small proportions of methane and ammonia

Question 6

Oceans formed

Answer 6

• first bn years
• water vapour condenseed
• co2 dissolved- carbonates precipitates- sediment

Question 7

2.7bn years ago

Answer 7

• algae firs produced 02

- esp photosynthesising algae in water

Question 8

Over nextbn years

Answer 8

• plants evolved as the 02 conc increased

- enabling animals to absorb

Question 9

Why did co2 levels decrease

Answer 9

• photosynthesising algae used c02

- formation sedimentary rocks and fossil duels containing carbon

Question 10

Complete combustion equation

Answer 10

Alkane + o2 = carbon dioxide + steam

Question 11

Incomplete combustion

Answer 11

• when not enough oxygen to burn the entirity of hydrocarbon molecule
  
  • restricted 02 supply
  • too large molecule

Alkane + oxygen = carbon ioxide +carbon monoxide + carbon+ steam

Question 12

Carbon monoxide

Answer 12

• CO
• poisenous gas
  
  • bonds permanently to heamogllobin
  • reducing body ability to transport o2
• become sleepy and unconscous-asphyxiate-colourless and odorless
• hard to detect- dosnt smll and is colourless

Question 13

Nitrous oxide

Answer 13

NOx

• in car petrol engins high enough to allow nitrogen and o2 from air to react forming oxygens of nitrigen
  
  • due to spark plugs in cylindeers
• can cause breathing difficulties
• can lead to acid rain or smog

Question 14

Soot

Answer 14

• particulates caused by incomplet combustion
• when inhaled- repiritary problems(esp if asmatic), heart disease, lung disease and cancer
• can blacken buildings

Question 15

How is acid rain form

Answer 15

Nitrous oxide or sulfu dioxide dissolve into water

Question 16

Consequenes of acid rain

Answer 16

• damage to trees
• acidification of lakes-affecting fish
• damages limestone and some buildings

Question 17

Sulfur dioxide

Answer 17

• combustion of some impurities in hydrocarbon fuels results in formation of sulfur dioxide
• sulfur atoms from crude oil
  
  • sulfur atoms in living organisms
• sulfur reacts with oxygen n air
• dissolves into water to form acid rain