HSC 2012-2015 Chemistry Marathon (archive) (3 Viewers)

[bangladesh]

re: HSC Chemistry Marathon Archive

No idea tbh

edit: For heavy metals I did the sulfide test(qualitative) and for eutrophication I did the two tests mentioned above

Yeah, I personally highly doubt that they ask you specifically to for example say how to monitor nitrate levels because 99.5% of students won't know that and will probs make up stuff like AAS. However I think what that dot point wants students to do is to know What Eutrophication is and what stimulates it and how it could be prevented/ tested rather than learning tests for every single component that contributes to Eutrophication.
However it's still good to learn what you posted, in case they give it, so thanks for posting that question.

EDIT: For heavy metals, be sure to include AAS as well as very very low conc cannot be tested that way.

 

[Frie]

re: HSC Chemistry Marathon Archive

Question: Outline two differences between halons and CFCs.

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

Question: Outline two differences between halons and CFCs.

1) Halons have bromine atoms, CFCs don't
2) Halons has a higher ozone depletion potential than CFCs as bromine radicals are more dangerous than chlorine radicals

Question: Assess current developments in the use of biopolymers. 5M or Explain how O2 and O3 have different physical and chemical properties despite both being allotropes of oxygen. 4m

gonna bump this

 

[hamstar]

re: HSC Chemistry Marathon Archive

Question: Assess current developments in the use of biopolymers. 5M or Explain how O2 and O3 have different physical and chemical properties despite both being allotropes of oxygen. 4m

Research in biopolymers have become important to overcome the society's need as the petroleum derived products are becoming limited due to the heavy use by society. Biopolymers are a renewable source of energy which leads to the overcoming of this major challenge faced by the society.
Polyhydroxyalkanoates (PHA) are natural biopoymers synthesised from bacteria such as Alcaligenes Eutrophus. One of these PHA is PHB (polyhydroxybutanoate).
To produce this biopolymer, the micro-organism is fed nutrients so it multiplies rapidly. The diet of the organism is changed to restrict the supply of one specific nutrient, such as nitrogen. Under these conditions, the organism is no longer able to increase it's population but instead begins to make the desired polymer. The organism is harvested and the polymer is separated out.

The biopolymer, PHB, has similar properties to polypropylene, an addition polymer derived from fossil fuels. PHB is stable in air, however in anaerobic conditions is attacked and is decomposed by anaerobic bacteria. This makes this biopolymer significant than the petroleum based polymer, polypropylene, as it does not contribute to landfill. PHB is used in the production for plastic films, bottles, medical and hospital supplies and due to it's property of being biocompatible, it is used in medicine and pharmaceutical purposes.
However, research needs to be carried on, as the cost of biopolymers makes it impractical to be used in the society.
Hence scientists have extended their research methods to produce biopolymers by using genetic engineering methods, such as using E. Coli, and using transgenic species to make biopolymers as a viable method to be used in society.

 

[bedpotato]

re: HSC Chemistry Marathon Archive

Research in biopolymers have become important to overcome the society's need as the petroleum derived products are becoming limited due to the heavy use by society. Biopolymers are a renewable source of energy which leads to the overcoming of this major challenge faced by the society.
Polyhydroxyalkanoates (PHA) are natural biopoymers synthesised from bacteria such as Alcaligenes Eutrophus. One of these PHA is PHB (polyhydroxybutanoate).
To produce this biopolymer, the micro-organism is fed nutrients so it multiplies rapidly. The diet of the organism is changed to restrict the supply of one specific nutrient, such as nitrogen. Under these conditions, the organism is no longer able to increase it's population but instead begins to make the desired polymer. The organism is harvested and the polymer is separated out.

The biopolymer, PHB, has similar properties to polypropylene, an addition polymer derived from fossil fuels. PHB is stable in air, however in anaerobic conditions is attacked and is decomposed by anaerobic bacteria. This makes this biopolymer significant than the petroleum based polymer, polypropylene, as it does not contribute to landfill. PHB is used in the production for plastic films, bottles, medical and hospital supplies and due to it's property of being biocompatible, it is used in medicine and pharmaceutical purposes.
However, research needs to be carried on, as the cost of biopolymers makes it impractical to be used in the society.
Hence scientists have extended their research methods to produce biopolymers by using genetic engineering methods, such as using E. Coli, and using transgenic species to make biopolymers as a viable method to be used in society.

what? i dont think thats right?

 

[ocatal]

re: HSC Chemistry Marathon Archive

I used the tests for BOD and DO for this. Is that wrong...?

That should be correct. A low dissolved oxygen level and high BOD indicate possibilities of eutrophication.

 

[someth1ng]

Research in biopolymers have become important to overcome the society's need as the petroleum derived products are becoming limited due to the heavy use by society. Biopolymers are a renewable source of energy which leads to the overcoming of this major challenge faced by the society.
Polyhydroxyalkanoates (PHA) are natural biopoymers synthesised from bacteria such as Alcaligenes Eutrophus. One of these PHA is PHB (polyhydroxybutanoate).
To produce this biopolymer, the micro-organism is fed nutrients so it multiplies rapidly. The diet of the organism is changed to restrict the supply of one specific nutrient, such as nitrogen. Under these conditions, the organism is no longer able to increase it's population but instead begins to make the desired polymer. The organism is harvested and the polymer is separated out.

The biopolymer, PHB, has similar properties to polypropylene, an addition polymer derived from fossil fuels. PHB is stable in air, however in anaerobic conditions is attacked and is decomposed by anaerobic bacteria. This makes this biopolymer significant than the petroleum based polymer, polypropylene, as it does not contribute to landfill. PHB is used in the production for plastic films, bottles, medical and hospital supplies and due to it's property of being biocompatible, it is used in medicine and pharmaceutical purposes.
However, research needs to be carried on, as the cost of biopolymers makes it impractical to be used in the society.
Hence scientists have extended their research methods to produce biopolymers by using genetic engineering methods, such as using E. Coli, and using transgenic species to make biopolymers as a viable method to be used in society.

This can be much more concise. The first half is almost completely irrelevant.

The second half is mostly listing of properties but very little analysis.

1/5

 

[bangladesh]

re: HSC Chemistry Marathon Archive

This can be much more concise. The first half is almost completely irrelevant.

The second half is mostly listing of properties but very little analysis.

1/5

I agree. He wen offtopic which would cause him to lose marks. However i still believe that it'd be at least 2/5. I know HSC marking is harsh but.. not 1..

Ps. Anyone have the model answer for this question?

 

[Menomaths]

re: HSC Chemistry Marathon Archive

I agree. He wen offtopic which would cause him to lose marks. However i still believe that it'd be at least 2/5. I know HSC marking is harsh but.. not 1..

Ps. Anyone have the model answer for this question?

Nope, going off topic doesn't cost marks. Marks are awarded, not deducted (unless if you're contradicting and if the marking guideline says 'is concise' or something along those lines, but that's very uncommon)

 

[Sy123]

re: HSC Chemistry Marathon Archive

 

[Sy123]

re: HSC Chemistry Marathon Archive

 

[superSAIyan2]

re: HSC Chemistry Marathon Archive

also the question asks for biopolymerS - so talk about another biopolymer such as cellulose.

Also you must state what the developments are. E.g. biopol is biocompatible (able to be used in the body without rejection) and is being used in medical sutures and implants. This has been quite successful. Also it has similar properties to polyethylene and so research is aimed at replacing petroleum derived plastics with biopol. However this has seen very limited commercial use as Biopol is very expensive to make and requires lots of technical expertise.
This itself should be worth 2 marks as it mentions current developments and includes an appropriate judgement.

 

[bangladesh]

re: HSC Chemistry Marathon Archive

Nope, going off topic doesn't cost marks. Marks are awarded, not deducted (unless if you're contradicting and if the marking guideline says 'is concise' or something along those lines, but that's very uncommon)

By going offtopic and losing marks i didn't mean that he'd lose marks for going off topic. I meant that he focused on the wrong thing and his answer provided little description of what the question was actually asking which is why he'd get a poor mark. I just worded it incorrectly.

 

[bangladesh]

re: HSC Chemistry Marathon Archive

I can't really think of anyway to answer this without using a series of equations/graph. How many marks is it?

 

[Sy123]

re: HSC Chemistry Marathon Archive

I can't really think of anyway to answer this without using a series of equations/graph. How many marks is it?

4 marks (its those steps like initiation, propogation etc)

 

[bedpotato]

re: HSC Chemistry Marathon Archive

also the question asks for biopolymerS - so talk about another biopolymer such as cellulose.

Also you must state what the developments are. E.g. biopol is biocompatible (able to be used in the body without rejection) and is being used in medical sutures and implants. This has been quite successful. Also it has similar properties to polyethylene and so research is aimed at replacing petroleum derived plastics with biopol. However this has seen very limited commercial use as Biopol is very expensive to make and requires lots of technical expertise.
This itself should be worth 2 marks as it mentions current developments and includes an appropriate judgement.

You don't have to. As long as you have one detailed example, you should get the marks.

The marking guidelines for 3-4 (the question I have is only worth 4 marks) marks were:
- names a recent development of a named biopolymer
- states desirable properties of biopolymer
- identifies properties of biopolymer that allow an impact on society and environment
- makes a judgement about the impact of the biopolymer on both society and the environment

 

[ocatal]

re: HSC Chemistry Marathon Archive

Question: Identify and describe a device used to detect non-ionising radiation.

 

[bangladesh]

re: HSC Chemistry Marathon Archive

4 marks (its those steps like initiation, propogation etc)

Yes yes. I know what the answer is but i always use equations and diagrams to express each step. Eg peroxide opening up and attaching to the monomer etc etc. which would take like 10mins for me to type up haha.

 

[Sy123]

re: HSC Chemistry Marathon Archive

Yes yes. I know what the answer is but i always use equations and diagrams to express each step. Eg peroxide opening up and attaching to the monomer etc etc. which would take like 10mins for me to type up haha.

Oh ok I see, yea true you probably would need a diagram

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[superSAIyan2]

re: HSC Chemistry Marathon Archive

You don't have to. As long as you have one detailed example, you should get the marks.

[/I]

I took the question from HSC 2002 and the marking notes says : Where a question asks for plural responses, as indicated by developments and biopolymers, candidates must supply more than one example in their answer. A question asking about current developments calls for a response describing recent developments.

I thought this means you had to mention2 biopolymers. Or dos it mean you had to mention 2 recent developments?