chem 2 - chemistry of the atmosphere

Question 1

why did the percentage of carbon d decrease in the earths early atmosphere (4)

Answer 1

• volcanic activity released water vapour which condensed to form oceans
• carbon d dissolved in sea water
• formation of sediments, made of carbonates
• algae and plants evolved and absorbed carbon d by photosynthesis

Question 2

how long ago was earth formed

Answer 2

4.6 billion years ago

Question 3

how much has the percentage of nitrogen and oxygen changed from the earths early atmosphere till now
what about the other gases in the atmosphere today?

Answer 3

nitrogen - increased about 40 x (80%)
oxygen - increased about 21 x (20%)
less than 1% small amounts of other gases

Question 4

why did the percentage of oxygen increase in the early earths atmosphere

Answer 4

• algae and plants evolved which released oxygen by photosynthesis

Question 5

glucose is produces when algae photosynthesise

name 2 naturally occuring polymers produced from glucose

Answer 5

starch
cellulose

Question 6

describe shape and structure of a dna polymer (3)

Answer 6

• 2 polymer chain
• 4 different monomers
• double helix

Question 7

how do greenhouse gases trap energy from the sun

Answer 7

they absorb the long wavelength radiation thats reflected back off the surface

Question 8

explain what the 2 effects of burning sulfur are

Answer 8

• sulfur dioxide produced, causes acid rain, that damages buildings and trees
• soot produced, which are particulates, that cause global dimming

Question 9

3 reasons solar energy may not be able to replace fossil fuels for generating electricity

Answer 9

• sunshine is unreliable
• increased demand for energy
• lack of space

Question 10

what do nitrogen oxides do to the environment

Answer 10

negative impact
as they cause acid rain
which destroys trees

Question 11

how are fossil fuels formed (3)

Answer 11

• plants and plankton die
• they get buried by layers of sediment
• over millions of years they become compressed and form sedimentary rocks, oil and gas

Question 12

what specifically are crude oil and natural gas made from

Answer 12

formed from plankton

Question 13

what specifically is coal made from

Answer 13

sedimentary rock formed from plant deposits

Question 14

what 4 gases built up due to volcanic acitivty in earths early atmosphere

Answer 14

• nitrogen
• water vapour
• methane small (small amounts)
• ammonia (small amounts)

Question 15

describe the whole greenhouse effect (4)

Answer 15

-short incoming wavelengths are not absorbed
-but they absorb the long wavelength radiation thats reflected back off the surface
-then they re- radiate it in other directions towards the earth
-longwavelength radiation is thermal radiation, which warms the surface of the planet

Question 16

define carbon footprint

Answer 16

amount of carbon d and other greenhouse gases released over the full life cycle of something

Question 17

3 things that reduces amount of greenhouse gases and subsequentally their carbon footprint

Answer 17

• renewable energy sources used instead of fossil fuels
• gov could tax companies on the amount of greenhouse gases they emit e.g taxing cars
• tech that capture carbon d before its released to the atmosphere and stores it deep underground in oil wells

Question 18

3 climate change effects

Answer 18

• melting ice caps - causes sea levels to rise, increase flooding
• rainfall patterns changing - so areas don’t get enough water
• frequency and severity of storms increase