Topic 9 - chemistry of the atmosphere

Question 1

what do scientists believe the first billion years of earths history was like

Answer 1

the surface was covered in volcanoes that erupted and released lots of gases
the early atmosphere was mostly carbon dioxide with virtually no oxygen , similar to the atmosphere of mars and venus today.
volcanic activity released nitrogen whcih built up in the atmosphere over time as well as water vapour and small amounts of methane and ammonia.
when the water vapour in the atmosphere condensed it formed oceans
lots of carbon dioxide was removed as it dissolved in the oceans . this dissolved carbon dioxide then went through a series of reactions to form carbonate precipitates that formed sediments on the seabed.
green plants and algae evolved and absorbed some of the carbon dioxide so that they could carry out photosynthesis. later marine animals evolved, their shells and skeletons contained carbonates from the oceans.
some of these organisms took in from the atmosphere and oceans became locked up in rocks and fossil fuels after organsisms died.

Question 2

how are sedimentary rocks, oil and gas formed

Answer 2

when plants ,plankton and marine animals die, they fall to the seabed and get buried by layers of sediment. over millions of years, they become compressed and form sedimentary rocks, oil and gas- trapping carbon within them and helping to keep carbon dioxide levels in the atmosphere reduced .

Question 3

what is coal

Answer 3

a sedimentary rock made from thick plant deposits

Question 4

what is limestone

Answer 4

sedimentary rokc
made of calcium carbonate deposits from the shellsl and skeletons of marine organisms

Question 5

what was the first plant to evolve and when

Answer 5

algae
2.7 billion years ago

Question 6

how did percentage of oxygen increase

Answer 6

more plants evolved

Question 7

what is the composition of the atmosphere

Answer 7

80 % nitrogen
20% oxygen
less than 1% other gases (e.g. co2 and water vapour

Question 8

how is crude oil and natural gas formed

Answer 8

formed from deposits of plankton
these fossil fuels form reservoirs under the seabed when they get trapped in rocks

Question 9

give examples of greenhouse gases and explain what they do in the atmosphere (greenhouse effect)

Answer 9

carbon dioxide, methane , water vapour
act like an insulating layer in the earths atmosphere
dont absorb incoming short wavelength radiation from the sun but absorb long wavelength radiation that gets reflected back off the earth .
then they re radiate it in all directions - including back towards the earth .
the longwave radiation is thermal radiation , so it results in warming of the surface of the earth .
this is the greenhouse effect.

Question 10

what human activities affect the amount of greenhouse gases in the atmosphere

Answer 10

deforestation - fewer trees means less co2 is removed from the atmosphere via photosynthesis
burning fossil fuels - carbon that was locked up in these fuels is released as co2
agriculture - more farm animals produce more methane through their digestive processes.
creating waste - more landfill sites and more waste from agriculture means more co2 and methane released by decomposition of waste

Question 11

wha do most scientists believe is causing an increase in the earths temperature

Answer 11

increased carbon dioxide from human activity

Question 12

how do we know that infornmation on climate change is reliable ,

Answer 12

it has been peer reviewed

Question 13

why is it hard to fully understand the earths climate

Answer 13

its so complex and there are so many variables
very hard to make a model that isnt oversimplified
this has led to speculation particularly in the media where stories may be biased or only some of the info is given

Question 14

what are possible consequences of climate change

Answer 14

an increase in global temperature could lead to polar ice caps melting - causing a rise in sea levels , increased flooding in coastal areas and coastal erosion
changes in rainfall patterns may cause some regions to get too much or too little water . this , along with changes in temperatures may affect the ability of certain regions to produce food.
the frequency and severity of storms may also increase
changes in temperature and the amount of water available in a habitat may affect wild species leading to differences in their distribution .

Question 15

what are carbon footprints

Answer 15

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

Question 16

why is measuring the carbon footprint of something difficult

Answer 16

there are so many factors to consider

Question 17

what are ways to reduce carbon footprints

Answer 17

renewable energy sources or nuclear energy could be used instead of fossil fuels
using more efficient processes could conserve energy and cut waste. lots of waste decomposes to release methane , so this will reduce methane emmisions .
governments could tax companies or individuals based on the amount of greenhouse gases they emit
governments can also put a cap on emissions of all greenhouse gases that companies make - then sell licences for emissions up to that cap .
there is also technology that captures the co2 produced by burning fossil fuels before it is released into the atmosphere. it can then be stored deep underground in cracks in the rock such as old oil wells.

Question 18

why is cutting emissions difficult

Answer 18

there is still a lot of work to be done on alternative technologies that result in lower co2 emissions .
a lot of governments are also worried that making these changes will impact on the economic growth of communities - which could be bad for people well being . particularly important for countries that are still developing .
hard to make international agreements to reduce emissions . most countries dont want to sacrifice their economic development if they think others wont do the same
individuals in developing countries need to make changes to their lifestyles. hard to make people do that if they dont want to and if they arent educated on how to make change and why

Question 19

how are particulates of soot and carbon monoxide produced

Answer 19

incomplete combustion of fossil fuels

Question 20

what is the danger of particulates in the air

Answer 20

if they are inhaled they can get stuck in the lungs and cause damage. this can lead to respiratory problems .
bad for the environment 0 they themselves or the clouds they produce , reflect sunlight back into space. this means that less light reaches the earth - causing global dimming

Question 21

why is carbon monoxide dangerous

Answer 21

can stop your blood from carrying oxygen around the body
does this by binding to the haemoglovin in your blood that normally carries o2 - so les oxygen is able to be transported round your body .
alack of oxygen in the blood can lead to fainting , a coma or even death
carbon monoxide doesnt have any colour or smell so its very hard to detect. this makes it even more dangerous

Question 22

where does sulfur dioxide come from

Answer 22

released during the combustion of fossil fuels such as coal that contain sulfur impurities - the sulfur in the fuel becomes oxidised

Question 23

how are nitrogen oxides created

Answer 23

from a reaction between the nitrogen and oxygen in the air, caused by the heat of the burning

Question 24

what is the danger of nitrogen oxides and sulfer dioxide

Answer 24

when these gases mix with clouds they form dilute sulfurinc acid or dilute nitric acid. this then fals as acid rain .
acid rain kills plants and damages buildings and statues
makes metal corrode
cam be bad for human health - cause respiratory problems if breathed in