Some of the questions are not really within the syllabus, but I shall answerthe ones I'm bothered to.
1. Troposphere -> Stratosphere -> Mesosphere -> Thermosphere
Temperature decreases, increases, decreases, increases with altitude respectively.
2. Not much is needed on this section.
3. Say the Earth has 100L of gas. 78% nitrogen, 21% oxygen and 1% argon (i'm rounding off).
Since theres 78% nitrogen, then we have 78L of nitrogen. Equal moles of Gas occupy equal volumes.
n(Nitrogen) = 78/24.79 = 3.1464 moles
n(Oxygen) = 21/24.79 = 0.8471 moles
n(Argon) = 1/24.79 = 0.04033
Percentage of moles of nitrogen = n(Nitrogen)/[(nitrogen + oxygen + argon)] = 78%
, same number for oxygen and argon.
6. Burning of fossil fuels, the petrol chemical industry.
8. Ozone is a reactive molecule as although it has a covalent bond, the co-ordinate covalent bond isn't as strong as the normal covalent bond, making it reactive.
9. O2 + UV -> O' + O'
O' + O2 -> O3
10. Electric sparks decompose oxygen gas to form radicals. Radicals bond with oxygen to form ozone.
13. Respiratory problems etc. etc.
14. UV is more prominent in the strato sphere, UV breaks down oxygen gas, forming radicals which bond to make ozone.
16. Acts as a UV radiation shield, minimising the amount of UV reaching earth.
17. If there is high UV radiation, this can cause health problems (ie. skin cancer)
19. Kills skin cells.
20. We're often at the beach and the ozone cocnentration above our country is relatively low, allowing more UV to to reach earth.
21. As a replacement for ammonia in refridgerators as they were non-toxic, inert and easily liquified.
25.
a)CCl3F + UV-> Cl' + CCl2F
b)Cl' + O3 -> ClO' + O2
c) Questions abit weird because I learnt natural break down of Ozone as -
O3 + UV -> O2 + O'
Then ClO' + O' -> Cl' + O2
26. The ClO' radical reacts with oxygen atom to form the Cl' radical and O2 gas. The Cl' radical production essentially repeats the chain again and again.
28. In a specific area, they shine a light of wavelength/frequency that is known NOT to be absorbed by ozone. They measure the intensity at the receiver. Then they shien another light that is KNOWN to be absorbed by ozone and the intensity is measured at the receiver. They then compare the intensities of the two lights to determine the concentration of ozone.
30. CFC's/chlorine radicals dissolved in ice caps, during October the ice-caps melt and release CFC's/chlorine radicals into the atmosphere which makes its way to the stratosphere.
32. Yes, it is a slow process. It'll depend on how quickly the CFC's present in the stratosphere break down (ie. Chlorine radical becomes a stable compound)
33. HFC (Hydrofluorocarbons) and HCFC (hydrochlorofluorocarbons)
34. They have been effective in the sense that they have very low ozone depletion potentials. HCFC's are also relatively reactive, hence they decompose in the troposphere before being able to reach the stratosphere. HFC's do not have chlorine, making their presence in the stratosphere negligible. They have been able to replace CFC's roles, but are often not as effective. They are also made of greenhouse gases, which effectively contributes to global warming upon release. Another disadvantage is that they are more expensive than CFCs to produce.
Despite this, HCFC's and HFC's have been a successful replacement to CFC's in minimising further damage done to the ozone layer, and despite their drawbacks - their ability to take roles as CFC's once did make them an essential replacement.
