possible biggie this year? (1 Viewer)

[Abtari]

ok, the syllabus dotpoint:

discuss the problems associated with the use of CFCs and assess the effectiveness of steps taken to alleviate these problems

when the syllabus says these problems i am assuming they are talking about the problems that are to be discussed in the first section. From my notes, all i have on the problems associated with the use of CFCs, is

1) the depletion of ozone layer
2) the resultant effects of that depletion...

i need to make sure I am covering everything for the 'problems' bit so i can answer the second part of that dotpoint.

ARE THERE ANY OTHER PROBLEMS ASSOCIATED WITH THE USE OF CFCs?

 

[rnitya_25]

CFC's aren't destroyed by low altitudies but sunlight, nor are they soluble in water to be washed out, so they remain in the atmosphere, for agess....decades. they slowly come into concact with UV rays, then cfc's break up to have a single Cl ion, and undergoes uv photodissociation to form a Cl free radical. these catalytically destroy the ozone layer, or they make it thinner, causing the ozone hole, and in turn allowng harmful UV rays to hit us humans. what is worse is that the Cl doesn't die off, it keeps reforming...that;s all you need to know. you also need to know the remedies and action taken to prevent the depletion of the ozone layer, such as the montreal protocol and the vienna convention. hope that helps..

 

[Abtari]

ok. this is where i wanted to get upto. Now that i know that the problems associated with the use of CFCs mainly concern ozone depletion and its effects, i move to the second part of that dotpoint:

assess effectiveness of steps taken to alleviate these problems

so alleviate ozone depletion

or

alleviate the effects of ozone depletion (cancer, polymer destruction, ecosystem imbalance, damage to molecules)

?????

 

[rama_v]

The only way to alleivate the problem is to stop using CFC's. These days they use HCFC's which have a much lower ozone dpeleting potential. Gradually they are using HFC's which have absolutely no ozone depleting potential. I think you will find that there was an international agreement in the UN in 1994, about phasing out CFC's - the developed countries pledged to support them financially in this process.

Make sure that you include the equations in the first part of it as well

 

[rnitya_25]

alleviate the ozone depletion. i asked that exact question on hsc advice line...and they only said that you need to know the effect on humans, not remedies put in place to alleviate how it affects humans, because if remedies are put in place to alleviate the ozone depletion, that will in turn lead to less harm on earth.

 

[Abtari]

im sorry but i dont follow what u are saying there rnitya...

my question is in the second part: assess effectiveness of steps taken to alleviate problems, do we talk about the effectiveness of steps taken to alleviate ozone depletion itself (e.g. less use of CFCs, introduction of HCFCs, HFCs, Montreal Protocol blabla) or do we talk about the effectiveness of steps taken to alleviate the EFFECTS of ozone depletion (e.g. sunscreen use, uv stabilisers in polymers etc)

 

[richz]

no this wont be asked they asked this one last year.........

 

[Rax]

I think you will find its alleviate the problems of Ozone depletion
IE Montreal Protocol
and replacing CFC's with HCFC's and HFC's

I hope it is in the HSC because thats easy marks all round

 

[sikeveo]

Yeh the montreal protocol was in the NEAP 2005 paper.

 

[Plebeian]

"Assessing the effectiveness" refers to steps taken to combat ozone depletion itself, not the effects of ozone depletion. However, last year's extended response question was:

Discuss the problems associated with the use of CFCs, and assess the suitability of alternative chemicals as replacements, using data in the table.

so it is unlikely to appear again.