HSC 2012-2015 Chemistry Marathon (archive) (4 Viewers)

[Crisium]

re: HSC Chemistry Marathon Archive

what are the bloody ozone equations??

i've seen like a billion of them in like a billion different orders.

Like im so confused.

I want: Ozone protecting us from UV eequations

AND

Ozone bein destroyed equations .

IN THE CORRECT ORDER !!! please somone

There is no equation for it protecting us

Just refer to it as a UV radiation shield in the upper atmosphere (stratosphere) which prevents harmful UV-B and UV-C from reaching us which would otherwise cause skin cancers, melanoma's, etc. but it allows UV-A through which is an essential source of Vitamin C

Ozone Depletion:

https://www.matrix.edu.au/chemical-...il&utm_term=0_37e76ca220-5bf6b4f918-352056969

Scroll down to the bottom

 

[Mr_Kap]

re: HSC Chemistry Marathon Archive

what about: O3 ---UV LIGHT-----> O2 + O radical ????

or O3 + O radical ---> 2O2 ???

 

[Kaido]

re: HSC Chemistry Marathon Archive

Protecting us:
O2 -(U.v.)> 2O
O + O2 -> O3
O3 -(U.v.)> O2 + O (this is the actual 'protecting', the others show how the cycle rinse and repeats)
O + O3 -> 2O2

CFC destruction:
CCl2F2 (g) -(UV)> Cl (g) + ·CClF2 (g)
·Cl (g) + O3 (g) -> ·ClO (g) + O2 (g)
·ClO (g) + O (g) -> ·Cl (g) + O2 (g) (Regen)

 

[aanthnnyyy]

re: HSC Chemistry Marathon Archive

Protecting us:
O2 -(U.v.)> 2O
O + O2 -> O3
O3 -(U.v.)> O2 + O (this is the actual 'protecting', the others show how the cycle rinse and repeats)
O + O3 -> 2O2

CFC destruction:
CCl2F2 (g) -(UV)> Cl (g) + ·CClF2 (g)
·Cl (g) + O3 (g) -> ·ClO (g) + O2 (g)
·ClO (g) + O (g) -> ·Cl (g) + O2 (g) (Regen)

This also occurs correct?
NO2--(UV)--> NO + O
O + O2 ---> O3
That is the photochemical smog occurring from combustion of engines abundant during days with high UV

 

[Drsoccerball]

re: HSC Chemistry Marathon Archive

This also occurs correct?
NO2--(UV)--> NO + O
O + O2 ---> O3
That is the photochemical smog occurring from combustion of engines abundant during days with high UV

Those reactions look like the reduction of photochemical smog lol ?

 

[Crisium]

re: HSC Chemistry Marathon Archive

This also occurs correct?
NO2--(UV)--> NO + O
O + O2 ---> O3
That is the photochemical smog occurring from combustion of engines abundant during days with high UV

Yeah

+ Don't forget to mention how stratospheric methane ends the ozone depletion chain reaction

 

[Crisium]

re: HSC Chemistry Marathon Archive

Those reactions look like the reduction of photochemical smog lol ?

...

Sunlight reacts with nitrogen dioxide to form photochemical smog, peroxyacylnitrates (PAN), etc. <-- We learnt this from The Acidic Environment

 

[Anousha]

re: HSC Chemistry Marathon Archive

can someone explain to me HOW ozone destruction is accelerated in Spring, particularly in Antarctica ???????

 

[Drsoccerball]

re: HSC Chemistry Marathon Archive

can someone explain to me HOW ozone destruction is accelerated in Spring, particularly in Antarctica ???????

Theres more uv lel

 

[Anousha]

re: HSC Chemistry Marathon Archive

Theres more uv lel

'explain' hahah

 

[pomsky]

re: HSC Chemistry Marathon Archive

Yeah

+ Don't forget to mention how stratospheric methane ends the ozone depletion chain reaction

What do you mean by this. Is this in the syllabus?

 

[Kaido]

re: HSC Chemistry Marathon Archive

What do you mean by this. Is this in the syllabus?

No, it's unnecessary to mention it.

 

[monopoly73]

re: HSC Chemistry Marathon Archive

Explain whether KOH can be used to make a suitable standard solution. 3 MARKS.

a suitable standard solution should be readily available, found in pure form and unreactive. KOH can be found in pure form and can be sold in pellets making it easy to transport and weight. however KOH is hygroscopic meaning it absorbs moisture from the air making it reactive. because of this it cannot be used as a suitable standard solution.
hope this is right!

 

[Crisium]

re: HSC Chemistry Marathon Archive

No, it's unnecessary to mention it.

It's in the syllabus

You should probably learn it if you want that 96+ ...

 

[Kaido]

re: HSC Chemistry Marathon Archive

It's in the syllabus

You should probably learn it if you want that 96+ ...

Oh really, if you could point out which DP, I'd appreciate it.

From the student answers I've seen in the last few years, none have mentioned that and have still received full marks when talking about Ozone depletion etc.
Then again, no questions have asked "how to remove ozone in the troposphere" specifically

 

[Crisium]

re: HSC Chemistry Marathon Archive

'explain' hahah

With what I mentioned to Kaido you need to know how ozone depletion is naturally stopped - There is a build up of compounds (these compounds are formed with the natural reactions that prevent ozone depletion) originating from stratospheric methane and nitrogen dioxide that combine to form more mo0lecular chlorine

Since the Antartic winters are constantly dark these compounds build up due to the Antartic winds and when Spring comes around there is finally U.V radiation and since there is a greater source of chlorine to act on there is a greater degree of ozone depletion

Sorry for the dodgy wording, I'm still trying to find a way to express it clearly :/

 

[rand_althor]

re: HSC Chemistry Marathon Archive

What do you mean by this. Is this in the syllabus?

Methane reacts with a chlorine atom to form hydrogen chloride and a methyl radical. . This prevents that chlorine atom from partaking in the destruction of the ozone. (Check page 254 of Conquering Chemistry)

 

[rand_althor]

re: HSC Chemistry Marathon Archive

Not sure if this question has popped up before:

Compare the chemical processes involved in the production of polyethylene and a named biopolymer (not cellulose) and evaluate the effect on society and the environment of both types of polymers. (7 marks)

 

[Mr_Kap]

re: HSC Chemistry Marathon Archive

Not sure if this question has popped up before:

Compare the chemical processes involved in the production of polyethylene and a named biopolymer (not cellulose) and evaluate the effect on society and the environment of both types of polymers. (7 marks)

I really dont know how to get 7 marks. Like i can only find differences between them not similarities.

Can you put in dot points what you need to mention for full marks.

 

[Kaido]

re: HSC Chemistry Marathon Archive

I really dont know how to get 7 marks. Like i can only find differences between them not similarities.

Can you put in dot points what you need to mention for full marks.

Ultimately, you're producing long chained polymers that can be used in the polymer industry/market. Probably mentioning one similarity is enough, since it's mainly differences