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October 14, 2025, 09:52:40 am

Author Topic: HSC Chemistry Question Thread  (Read 1294215 times)  Share 

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Fahim486

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Re: Chemistry Question Thread
« Reply #2415 on: July 16, 2017, 06:04:37 pm »
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Hi again I've got another question, do LDPE have strong intermolecular forces or weak intermolecular forces? Thanks!

MisterNeo

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Re: Chemistry Question Thread
« Reply #2416 on: July 16, 2017, 06:52:19 pm »
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Hi, I'm confused as to how you would approach this question on addition polymers. Thanks!
Hi! :)
For this question you would explain how a longer polymer chain results in those properties based on the flowchart. You just need to structure your response according to what is given by the flowchart. A longer chain results in higher dispersion forces that increase the intermolecular forces between polymer chains, hence high melting/boiling points and increased hardness.
Hi again I've got another question, do LDPE have strong intermolecular forces or weak intermolecular forces? Thanks!
LDPE have weaker intermolecular forces than HDPE because the frequent side branching prevents proper alignment of atoms, thus reducing the strength of the dispersion forces.  ;D

seventeenboi

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Re: Chemistry Question Thread
« Reply #2417 on: July 16, 2017, 08:54:08 pm »
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hello
for the question 'state 3 ways that AAS has had a great impact on scientific understanding of tracelements in organisms' .. how would you answer it in a detailed way .. i'm also having trouble coming up with answers ??

so far I can only really think of
1. the essentiality of trace elements as they aid enzyme function - their requirement for the proper functioning of organisms in biological systems (i.e. iron in haemoglobin, magnesium, calcium, zinc in our systems)
2. criticality of trace element deficiencies in organisms - in humans, lack of micronutrients in plants, lack of cobalt on pasteur land, so animal health could not be maintained ..
3. ?????

could it possibly that the discovery of trace elements itself be considered an 'impact'??
in what other ways could you answer this question ?
thanks :)

Natasha.97

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Re: Chemistry Question Thread
« Reply #2418 on: July 16, 2017, 09:23:01 pm »
+4
hello
for the question 'state 3 ways that AAS has had a great impact on scientific understanding of tracelements in organisms' .. how would you answer it in a detailed way .. i'm also having trouble coming up with answers ??

so far I can only really think of
1. the essentiality of trace elements as they aid enzyme function - their requirement for the proper functioning of organisms in biological systems (i.e. iron in haemoglobin, magnesium, calcium, zinc in our systems)
2. criticality of trace element deficiencies in organisms - in humans, lack of micronutrients in plants, lack of cobalt on pasteur land, so animal health could not be maintained ..
3. ?????

could it possibly that the discovery of trace elements itself be considered an 'impact'??
in what other ways could you answer this question ?
thanks :)

Hi! :)

I think you're on the right track for the first and second points! The third way could possibly be measuring the concentration of toxic ions such as lead, as it is toxic to the body (brain, kidneys, neurotoxin). As for the level of detail, it is all dependent on the number of marks this is worth (e.g. if it is 6 marks, 3 would be the ways that AAS has an impact, and the other 3 would be an explanation of why it had a great impact). Hope this helps :D
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kiwiberry

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Re: Chemistry Question Thread
« Reply #2419 on: July 16, 2017, 09:27:05 pm »
+3
hello
for the question 'state 3 ways that AAS has had a great impact on scientific understanding of tracelements in organisms' .. how would you answer it in a detailed way .. i'm also having trouble coming up with answers ??

so far I can only really think of
1. the essentiality of trace elements as they aid enzyme function - their requirement for the proper functioning of organisms in biological systems (i.e. iron in haemoglobin, magnesium, calcium, zinc in our systems)
2. criticality of trace element deficiencies in organisms - in humans, lack of micronutrients in plants, lack of cobalt on pasteur land, so animal health could not be maintained ..
3. ?????

could it possibly that the discovery of trace elements itself be considered an 'impact'??
in what other ways could you answer this question ?
thanks :)

Hey! In addition to the above answer, you should definitely mention the fact that the development of AAS led to the discovery of trace elements in the first place - previous methods like gravimetric analysis were not sensitive enough to detect the presence of trace elements and so the causes of deficiency diseases in humans and plants were unknown. AAS was sensitive and accurate enough to detect their presence, and so a correlation between these elements and the health of organisms could be drawn. You can then talk about the points you mentioned about the importance of trace elements. :)
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winstondarmawan

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Re: Chemistry Question Thread
« Reply #2420 on: July 17, 2017, 12:44:46 am »
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Hello! Some questions for shipwrecks.
So, my notes says increasing temperature increases rate of corrosion. However, doesn't increasing temperature also result in reducing of solubility of gases (e.g. O2), which wold reduce the rate of corrosion?
Also, I don't understand how there can be anaerobic corrosion, according to this solution:
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/20136777_1272903182835202_353827078_n.png?oh=dd044f1c45b808da2e920e39970ce5c3&oe=596E7E05
TIA!

MisterNeo

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Re: Chemistry Question Thread
« Reply #2421 on: July 17, 2017, 01:13:58 am »
+2
Hello! Some questions for shipwrecks.
So, my notes says increasing temperature increases rate of corrosion. However, doesn't increasing temperature also result in reducing of solubility of gases (e.g. O2), which wold reduce the rate of corrosion?
Also, I don't understand how there can be anaerobic corrosion, according to this solution:
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/20136777_1272903182835202_353827078_n.png?oh=dd044f1c45b808da2e920e39970ce5c3&oe=596E7E05
TIA!

According to the EasyChem website (I don't do shipwreck sorry :P), the oxygen solubility does decrease but it's negligible because most corrosion is done by anaerobic bacteria at depths.
Anaerobic bacteria corrode by reducing sulfate to hydrogen sulfide ion using electrons from iron. (This explains it all.)


winstondarmawan

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Re: Chemistry Question Thread
« Reply #2422 on: July 17, 2017, 08:51:51 am »
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According to the EasyChem website (I don't do shipwreck sorry :P), the oxygen solubility does decrease but it's negligible because most corrosion is done by anaerobic bacteria at depths.
Anaerobic bacteria corrode by reducing sulfate to hydrogen sulfide ion using electrons from iron. (This explains it all.)



Thank you! Also, does a non-Industrial student need to know equilibrium constant?

jakesilove

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Re: Chemistry Question Thread
« Reply #2423 on: July 17, 2017, 11:48:19 am »
+1
Thank you! Also, does a non-Industrial student need to know equilibrium constant?

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hansolo9

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Re: Chemistry Question Thread
« Reply #2424 on: July 18, 2017, 11:51:12 pm »
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Hi :) can some who does industrial chem help me with this question?

"Explain why sulfuric acid is added into water instead of water being added into sulfuric acid?"
TIA

MisterNeo

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Re: Chemistry Question Thread
« Reply #2425 on: July 18, 2017, 11:53:29 pm »
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Hi :) can some who does industrial chem help me with this question?

"Explain why sulfuric acid is added into water instead of water being added into sulfuric acid?"
TIA

Hey! So the reason why the pure acid is added to the water and not vice versa is solely because acid ionisation is exothermic.
If you were to add a beaker of acid to a beaker of water, the first drop of acid being ionised make the solution dilute and not pose any threat from the heat released.
However, if you were to add a beaker of water to a beaker of acid, the first drop of water will make the solution an extremely high concentration, and the exothermic reaction can boil the water and spray concentrated acid everywhere. Thus, fuck up your day - and your experiment.
So the general rule here is acid first so it doesn't burst. ;D

bigsweetpotato2000

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Re: Chemistry Question Thread
« Reply #2426 on: July 19, 2017, 01:17:35 am »
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To start the exams with the Multiple Choice or to not start the exams with the Multiple Choice?

Especially for chemistry since the multiple choice is quite hard to tackle  :o

Thanks!

Bigsweetpotato Farm

MisterNeo

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Re: Chemistry Question Thread
« Reply #2427 on: July 19, 2017, 01:58:12 am »
+1
To start the exams with the Multiple Choice or to not start the exams with the Multiple Choice?

Especially for chemistry since the multiple choice is quite hard to tackle  :o

Thanks!

Bigsweetpotato Farm

I would have a look through MC during reading time to get an idea on how much time you should allocate for the section.
Personally, I like to do the first half of the MC at the start, then do the rest in between other sections to give my hand a break from the longer responses. ;)

Shadowxo

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Re: Chemistry Question Thread
« Reply #2428 on: July 19, 2017, 10:39:53 am »
+1
To start the exams with the Multiple Choice or to not start the exams with the Multiple Choice?

Especially for chemistry since the multiple choice is quite hard to tackle  :o

Thanks!

Bigsweetpotato Farm

What I tend to do is see how much time the MC questions are worth with respect to marks. Then, I use reading time to look over SA questions and get an idea of what they're talking about, and complete those first. I leave MC until the end unless I'm struggling with a SA question, if I am struggling I take a break and either go to the next question or MC to give myself time to think about it.
- You can guess MC questions but not SA
- SA you have to include all relevant information, but in MC you only need the right answer
- MC questions are only worth 1 mark and past questions don't affect current answers
- Towards the end of the exam you're likely to be more tired and don't want to do those long tough questions

Just what I tend to do :)
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