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jakesilove

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Chemistry Question Thread
« on: January 28, 2016, 08:00:25 pm »
+15
HSC CHEMISTRY Q&A THREAD

To go straight to posts for the new syllabus, click here.

What is this thread for?
If you have general questions about the HSC Chemistry course or how to improve in certain areas, this is the place to ask! 👌


Who can/will answer questions?
Everyone is welcome to contribute; even if you're unsure of yourself, providing different perspectives is incredibly valuable.

Please don't be dissuaded by the fact that you haven't finished Year 12, or didn't score as highly as others, or your advice contradicts something else you've seen on this thread, or whatever; none of this disqualifies you from helping others. And if you're worried you do have some sort of misconception, put it out there and someone else can clarify and modify your understanding! 

There'll be a whole bunch of other high-scoring students with their own wealths of wisdom to share with you. So you may even get multiple answers from different people offering their insights - very cool.


To ask a question or make a post, you will first need an ATAR Notes account. You probably already have one, but if you don't, it takes about four seconds to sign up - and completely free!

OTHER CHEMISTRY RESOURCES

Original post.
Before you can ask a question, you'll have to make an ATAR Notes account here. Once you've done that, a little 'reply' button will come up when you're viewing threads, and you'll be able to post whatever you want! :)

Hey everyone!

A lot of you will have met me at the HSC Head Start lectures, where I lectured in 2U and 3U Maths, Physics and Chemistry.
My role on these forums is to help you. The HSC syllabus is tricky, nuanced and pretty damn huge. To help you out, I thought it would be a great idea to have a forum where you can just post questions, and myself or other forum members can post answers!

This is a community, so we want you to feel like you can post any type of Chemistry, no matter how "basic" you might think it is. Remember, IF YOU'RE HAVING TROUBLE WITH A TOPIC, THERE ARE THOUSANDS OF OTHERS HAVING THE SAME ISSUE. The best way to learn Maths is by looking through practice questions, and their associated answers. I honestly think a forum like this, and a place where I could always go to have difficult questions answered would have helped me in my HSC year.

Remember that Chemistry is a bloody difficult course. There will be lots of answers to the same questions, and I'll try give you the best or easiest to remember ones.

I got an ATAR of 99.80, and a mark of 93 in the Chemistry course. There are similar forums for a bunch of other subjects, so make sure to take a look at them as well!
« Last Edit: November 11, 2018, 03:34:03 pm by jamonwindeyer »
ATAR: 99.80

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Happy Physics Land

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Re: Chemistry Question Thread
« Reply #1 on: January 28, 2016, 09:47:35 pm »
+2
In 2007 HSC exam for chemistry, there was a question regarding "explain one benefit of car batteries lasting several years" and the notes from marking centre recommended that "Better responses clearly linked the benefit to a property of lead or sulfuric acid. Weaker responses did not give a specific benefit, but rather general statements that could have many meanings, such as ‘convenient and reliable’. The better responses explained such words in the context of their answers." I have some trouble trying to relate the property of lead or sulfuric to the question. Please Help Jake!!!
Mathematics: 96
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jakesilove

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Re: Chemistry Question Thread
« Reply #2 on: January 28, 2016, 10:19:34 pm »
+3
In 2007 HSC exam for chemistry, there was a question regarding "explain one benefit of car batteries lasting several years" and the notes from marking centre recommended that "Better responses clearly linked the benefit to a property of lead or sulfuric acid. Weaker responses did not give a specific benefit, but rather general statements that could have many meanings, such as ‘convenient and reliable’. The better responses explained such words in the context of their answers." I have some trouble trying to relate the property of lead or sulfuric to the question. Please Help Jake!!!

Hey Happy Physics Land (love the name by the way).

Great question, because it's the perfect example of the fact that sometimes teachers mark question in a way that is arbitrary and, to be frank, just wrong. The question, word for word, is "Explain one benefit of car batteries lasting several years." (from the 2007 paper, question 20b). This is framed in relation to an image of a Lead-Acid battery, however really the question doesn't ask specifically about a car battery with components that are Sulfuric acid or Lead. So really, an answer such as durability, convenience etc. should answer the question.

For a two mark question, make sure you talk about the positive attribute AND the reason its beneficial (ie. convenience of not having to replace battery regularly, resulting in greater costs to consumer, and safety, so that the battery doesn't die mid-drive).

The way the answer that you quote is phrased makes it seem like the question was "Explain how the components of the above battery make them suitable for car batteries". I really think the markers got that wrong, and in more recent exam papers you won't find such obvious misrepresentation of what the question was asking for.

The answer to the question "Explain how the components of the above battery make them suitable for car batteries" has many answers, including

1. The battery does not discharge much voltage whilst not in use, unlike many other forms of re-chargeable batteries
2. Results in a high voltage-discharge when required
3. Not easily subject to internal damage through corrosion etc.

However, like I've said I don't think these answers should have been required given the question. That being said, including as much information as possible is always a good idea when answering Chemistry questions, and so throwing one of these in could be a good idea if you want to play it safe.

I hope this helps: remember that you're only supposed to answer the question and, in this case, I think the marker got it wrong.

Jake :)
ATAR: 99.80

Mathematics Extension 2: 93
Physics: 93
Chemistry: 93
Modern History: 94
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Happy Physics Land

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Re: Chemistry Question Thread
« Reply #3 on: January 28, 2016, 11:23:30 pm »
+2
Thank you very much jake that was very helpful and it certainly assisted me in answering the question. Before you explained that to me I was also confused by the necessity to include "the properties of lead and sulfuric acid" in my answer. But that was really helpful a response, thank you very much matey!!!!

Best Regards

Happy Physics Land
Mathematics: 96
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thushan

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Re: Chemistry Question Thread
« Reply #4 on: January 29, 2016, 12:39:23 pm »
+7
I'm the corresponding ATARNotes Chemistry lecturer for VCE down in Victoria - I got a 50 (in VCE the maximum score you can get in a subject is 50).

Will lurk here and help answer questions too! But I will be coming from a Victorian slant.
« Last Edit: January 29, 2016, 12:55:42 pm by thushan »
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ghey04

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Re: Chemistry Question Thread
« Reply #5 on: January 31, 2016, 10:35:52 am »
0
Hey! I was wondering for the q "Analyse a recently developed biopolymer in terms of progress and method of production. Provide an evaluation of its potential of use" (5 marks) in Production of Materials (basically the dotpoint I guess), how would you write up the answer? I'm getting thrown off which part I should focus and write more on.

Happy Physics Land

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Re: Chemistry Question Thread
« Reply #6 on: January 31, 2016, 11:19:34 am »
+4
Hey! I was wondering for the q "Analyse a recently developed biopolymer in terms of progress and method of production. Provide an evaluation of its potential of use" (5 marks) in Production of Materials (basically the dotpoint I guess), how would you write up the answer? I'm getting thrown off which part I should focus and write more on.

Hello ghey04:

I am a year 12 student currently undertaking chemistry, just like yourself, and I am happy to help you out :) ! Ok so let's break down this question first since it consists of so many parts. Essentially the question asks us to do 5 things:
1. Identify this biopolymer (and perhaps even the year it was first developed)
2. How this biopolymer has developed in the society (i.e. is it widely used? Use statistics? state a use with slight references to its properties as an example. Is it becoming increasingly economical to produce?)
3. Identify and describe the method of production (Identify the bacteria/biomass required to produce this biopolymer (VERY IMPORTANT), describe the every single step of the procedure that is taken to produce this biopolymer)
4. Describe its current usage (list about 2 uses with slight reference to its properties)
5. Evaluate (i.e. make a judgement) the potential of the biopolymer in the future, and state your reason to back up your argument (e.g. this biopolymer has a significant potential for the society because as current technologies improve, this biopolymer can be produced more efficiently and economically. In conjunction with its ability to bio-degrade and the fact that it is produced from renewable resources, the production process of this biopolymer will be very sustainable and hence this biopolymer has a large potential to replace petrochemical polymers in both the contemporary and future society)

In regards to which part you should focus on, I think that both parts should be the same amount of writing. However, because you will be describing the method of production, and because the first question consists of essentially 3 parts, then I would put more concentration upon the first question. The ratio of writing between the two questions I would recommend is about 4 : 3. But please dont ignore the importance of the second question because it assesses how we can theoretically apply what we have learnt to predict the continual progress of the biopolymer into the future.

I hope this helps ghey04 and I wish you the best of luck throughout your HSC year!

Best Regards
Happy Physics Land
Mathematics: 96
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2017 ATAR: 99.70
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jakesilove

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Re: Chemistry Question Thread
« Reply #7 on: January 31, 2016, 11:23:45 am »
+3
Hey! I was wondering for the q "Analyse a recently developed biopolymer in terms of progress and method of production. Provide an evaluation of its potential of use" (5 marks) in Production of Materials (basically the dotpoint I guess), how would you write up the answer? I'm getting thrown off which part I should focus and write more on.

Hey ghey04!

Fantastic question, because really what a lot of Chemistry questions come down to is knowing what you are actually supposed to include in your answer.

I would always start off by underlining the important words. In this case, you need to analyse... progress and methods of production, and evaluate potential use. So that's exactly how I would structure your answer.

Start off by discussing the development of the biopolymer. Talk about its history/discovery, and any progress that has been made. You can summarise this in maybe two or three sentences. Then discuss how you produce the polymer, again in two or three sentences. Finally, discuss potential uses. I would definitely use subheadings for a 5 mark questions: teachers absolutely love it!

For instance, the structure would be:

History/Progress
Two/three sentences summarising important points. Try to include some specific facts!

Method of production
Two/three sentences explaining, fairly specifically, how we CURRENTLY develop the polymer. Try to include specific names of compounds etc.

Potential use
Two/three current uses, including WHY the biopolymer is useful in that scenario. For instance, polystyrene is a good material for a cup because it is an insulator, and will not heat up when boiling liquid is poured in.

I hope that helps! If you want to write up a response and post it here based on the above I am happy to comment on it :)

Jake
ATAR: 99.80

Mathematics Extension 2: 93
Physics: 93
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ghey04

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Re: Chemistry Question Thread
« Reply #8 on: January 31, 2016, 11:28:18 pm »
+2
Thanks HappyPhysicsLand and Jake! Really good stuff, I'll see how I go now :)

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Re: Chemistry Question Thread
« Reply #9 on: February 07, 2016, 12:40:34 am »
0
Consider the chemical equation below:
Br2(l) + 2Cl-(aq) --> 2Br-(aq) + Cl2(g)
Will this reaction occur spontaneously? Justify your response using relevant half-equations (3 marks)

Firstly, what defines a 'spontaneous reaction' in regards to galvanic cells, and how would you go about this question :/

Thanks!

Subjects: 3U Maths, Adv. English, Chemistry, Geography, PDHPE

jakesilove

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Re: Chemistry Question Thread
« Reply #10 on: February 07, 2016, 09:44:08 am »
+4
Consider the chemical equation below:
Br2(l) + 2Cl-(aq) --> 2Br-(aq) + Cl2(g)
Will this reaction occur spontaneously? Justify your response using relevant half-equations (3 marks)

Firstly, what defines a 'spontaneous reaction' in regards to galvanic cells, and how would you go about this question :/

Thanks!

Hey Wesadora!

Below is my solution to this (very difficult) question. Usually, you could get similar questions regarding metals (Sodium and Potassium Nitrate etc.) but I've never seen one like this. Hope it helps!



Jake
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Johny1234567

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Re: Chemistry Question Thread
« Reply #11 on: February 07, 2016, 10:41:15 am »
0
Hello!
I need help with the following question:

35mL of 0.86 M sulfuric acid was placed into a 25mL solution of 1.00 M sodium hydroxide.

b) Calculate the concentration hydrogen or hydrogen ions after this reaction. You may assume the reaction is complete. (3 marks)

c) Calculate the pH of the final solution. (1 mark)

d) If 5 drops of methyl orange was placed into the NaOH solution before the reaction took place, explain the colour changes that occur over the course of the experiment. (3 marks)

Any help would be greatly appreciated!

jakesilove

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Re: Chemistry Question Thread
« Reply #12 on: February 07, 2016, 11:43:20 am »
+3
Hello!
I need help with the following question:

35mL of 0.86 M sulfuric acid was placed into a 25mL solution of 1.00 M sodium hydroxide.

b) Calculate the concentration hydrogen or hydrogen ions after this reaction. You may assume the reaction is complete. (3 marks)

c) Calculate the pH of the final solution. (1 mark)

d) If 5 drops of methyl orange was placed into the NaOH solution before the reaction took place, explain the colour changes that occur over the course of the experiment. (3 marks)

Any help would be greatly appreciated!

Hey Johny!

These sort of "Concentration" questions are very typical, however this is one of the most difficult ones I've seen (mainly because of the difficulty of the chemical equation). However, if you are able to follow this working out and do lots of practice questions, you'll find this to be easy marks in the HSC! Hope that this helps!

If you don't quite understand a step, maybe submit another question that is similar, but easier. Once you have the general working out style, you'll be totally fine :)




Thanks for the great question!

Jake
ATAR: 99.80

Mathematics Extension 2: 93
Physics: 93
Chemistry: 93
Modern History: 94
English Advanced: 95
Mathematics: 96
Mathematics Extension 1: 98

Studying a combined Advanced Science/Law degree at UNSW

Happy Physics Land

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Re: Chemistry Question Thread
« Reply #13 on: February 07, 2016, 12:30:06 pm »
+1
Hey Johny!

These sort of "Concentration" questions are very typical, however this is one of the most difficult ones I've seen (mainly because of the difficulty of the chemical equation). However, if you are able to follow this working out and do lots of practice questions, you'll find this to be easy marks in the HSC! Hope that this helps!

If you don't quite understand a step, maybe submit another question that is similar, but easier. Once you have the general working out style, you'll be totally fine :)

(Image removed from quote.)
(Image removed from quote.)

Thanks for the great question!

Jake

Farrrrrr Jake you are on Fire..... Loving those explanations!
Mathematics: 96
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Johny1234567

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Re: Chemistry Question Thread
« Reply #14 on: February 07, 2016, 01:14:00 pm »
+1
Hey Johny!

These sort of "Concentration" questions are very typical, however this is one of the most difficult ones I've seen (mainly because of the difficulty of the chemical equation). However, if you are able to follow this working out and do lots of practice questions, you'll find this to be easy marks in the HSC! Hope that this helps!

If you don't quite understand a step, maybe submit another question that is similar, but easier. Once you have the general working out style, you'll be totally fine :)

(Image removed from quote.)
(Image removed from quote.)

Thanks for the great question!

Jake

Hello Jake,
Your explanation was clear and concise. Thank you !