HSC 2015 Chemistry Q&A Thread (1 Viewer)

[saif1788]

Ask any HSC chemistry question and will try to answer it or help answer other people's questions.

 

[Thunderstorm]

love iiiit

 

[justem]

I'm gonna be using this a lot


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[teridax]

explain w0t iz chem 2 mi pls

In all seriousness, is it true that HSC Chemistry involves a lot of memorising?

 

[saif1788]

There is a fair bit of memorizing yeah, facts, lists and comparisons between technologies, concepts and products. They want the student to be aware of the latest technologies and be able to demonstrate excellent researching skills (Find reliable academic resources etc.). In short , yes, there is plenty to memorize

 

[cricket95]

thanks

 

[dan964]

There is a fair bit of memorizing yeah, facts, lists and comparisons between technologies, concepts and products. They want the student to be aware of the latest technologies and be able to demonstrate excellent researching skills (Find reliable academic resources etc.). In short , yes, there is plenty to memorize

some of the course is what is called "rote learn", just memorize the facts. Most of topic 1 (all except redox and some ethanol stuff) and almost all of topic 3 is rote learn. Topic 2, requires a lot of applying chemistry more than memorizing facts; particularly in calculations etc.

 

[saif1788]

some of the course is what is called "rote learn", just memorize the facts. Most of topic 1 (all except redox and some ethanol stuff) and almost all of topic 3 is rote learn. Topic 2, requires a lot of applying chemistry more than memorizing facts; particularly in calculations etc.

Agreed. Carbon Carbon Chemistry (Alkanols / Ehanol) and Redox are conceptual, Acidic environment too.
So basically, a student can't get away with just memorizing content, it can cover a certain percentage (I don't know if I can dare say 30%) but a student needs understanding mostly (which helps the memorizing majorly).

 

[dan964]

Chemical Monitoring and Management is all rote learn, except for some of the practicals.

 

[turntaker]

Best way to study for chem?

and which textbook to use

 

[dan964]

Best way to study for chem?

and which textbook to use

best way to is to know your syllabus
and then get all the past HSC, CSSA etc. and then look at the mapping grids and do the questions per topic, as you go through syllabus.


textbooks: use more than one source
Conquering Chemistry is generally your best bet, except for nomenclature. Use Jacaranda for nomenclature
Jacaranda is good for the practicals, except don't use it for redox.
Dotpoint Chem is average. Macquarie Chem is too brief.
(I have some as .pdf if needed)

 

[iStudent]

I don't like Conquering. It's good for understanding but I don't think it goes into enough depth in some aspects required for the hsc. Also, I think BOSTES likes to take curveball questions from Jacaranda so your best bet is to use this. (e.g. the question on why neutralisation always gives the same heat of reaction 2011 - this was addressed directly in Jacaranda but those who only used Conquering wouldn't have a clue on how to answer this question).

 

[saif1788]

Best way to study for chem?

and which textbook to use

My opinion? Make your own notes!! It depends on which textbook you like the most. The best textbook would be the one that follows the syllabus. And the best way to learn it is by practising and starting from the basic concept upwards.

Example: I want to study redox reactions today.
I don't go straight to writing half equations. First I learn how to assign oxidation numbers, then learn how to write net ionic equations, then notice the changes in oxidation numbers (by looking at the net ionic equation with assigned oxidation numbers) then I split the reaction into half. So I am going a few steps back to learn the basics.

And you can do that by exploring textbooks, watching youtube, learning from friends etc. (So choose the text that looks appealing to you basically)

For an example of a layout of notes, view the sample resource here https://www.uhsinternational.com/hsc-chemistry-tutors.html

 

[aanthnnyyy]

This is usually a common one I think, "outline why ethanol is a useful solvent" with relevant diagrams blah blah

 

[Therese98]

Would someone please explain molar heat of combustion? (I'm so confused about it I'm not even sure if it's called that!)
Some worked examples would be great as well.

 

[saif1788]

Would someone please explain molar heat of combustion? (I'm so confused about it I'm not even sure if it's called that!)
Some worked examples would be great as well.

Molar heat of combustion:

Heat of combustion simply means the amount of heat released when burning something. When we burn 1 mole of that something we call the heat released molar heat of combustion.

So how do we calculate it?
Well, we burn a certain amount (say 5 grams) of something and see how much heat it releases.

Let us say for the sake of example it gave us 500j. We then say if 5 grams gives us 500j, how much would 1gram give us? (Simple maths) 1g gives us 100j.

Then we say how much does 1 mole of this substance weight (again simple maths, mass=number of moles X molar mass). We find for example 1 mole weighs 3grams.

Then we say if 1 gram gives us 100j then how much would 3 grams give us? The answer would be 300j.

So now we found what the molar heat of combustion is (heat released per mole).

In the ethanol experiment, we use the (delta) H = mC(delta) T.

m is the amount of water we used (weight in grams) and delta T is the change in temperature, and C is the constant 4.18.

Check out this example as well:

Question: In an experiment, 1.4g of butanol was burnt and the heat collected by a metal can containing
200g of water. The water temperature rose by 23oC.

Heat absorbed by water in the calorimeter:
ΔH = -mCΔT

= - 200 x 4.18 x 23
= - 19,228 J
≅19 kJ of heat released.

This is the heat released for 1.4g of butanol burnt.

∴ Heat of Combustion per gram = 19/1.4 = 13.57 kJ/g
≅14 kJ/g

Molar Mass (butanol) = 74.1g

∴ Molar Heat of Combustion = 13.57 x 74.1
≅ 1000 kJmol-1.


Hope that answers your question you can go to: https://www.uhsinternational.com/hsc-chemistry-tutors.html and download the sample resource it has got more explanation about molar heat of combustion

and share the link ;-)

 

[saif1788]

Agree, easy marks, everyone must score.

 

[Therese98]

Thank you very much!

 

[peri24]

ok.

 

[saif1788]

Thank you very much!

You are welcome

Good luck.