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

[HeroicPandas]

re: HSC Chemistry Marathon Archive

Just to make sure we did different papers, did you guys have a question saying 'Draw the curve of the Haber Process when the pressure is lowered' That's horribly worded but it was something similar to that. My teacher said he bought the trials and changed it completely so there's a possibility

Mine had, draw a LINE (lol)...(if the volume of the reaction vessel is doubled)

 

[hayabusaboston]

re: HSC Chemistry Marathon Archive

Just to make sure we did different papers, did you guys have a question saying 'Draw the curve of the Haber Process when the pressure is lowered' That's horribly worded but it was something similar to that. My teacher said he bought the trials and changed it completely so there's a possibility

Yes I did... I drew a curve which went vertically down then went across to time 2 (T2) going gradually down some more.

 

[Menomaths]

re: HSC Chemistry Marathon Archive

Yeah, that's exactly the question I had! No wonder the exam was so good. How much did you guys get? PM me if you don't want to say it publicly and I'll tell you what I got when I get my result back.

 

[hayabusaboston]

re: HSC Chemistry Marathon Archive

Yeah, that's exactly the question I had! No wonder the exam was so good. How much did you guys get? PM me if you don't want to say it publicly and I'll tell you what I got when I get my result back.

NAH WE MUST GO PUBLIC! lol ok I'll start from a certain point. Did we all get above 70/100? Or for heroicpandas, ur exam was cut down to 70 marks right?

 

[Menomaths]

re: HSC Chemistry Marathon Archive

Why was it cut down? No option included?

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

NAH WE MUST GO PUBLIC! lol ok I'll start from a certain point. Did we all get above 70/100? Or for heroicpandas, ur exam was cut down to 70 marks right?

Why was it cut down? No option included?

idk why it was cut down

anways im off cya

 

[Menomaths]

re: HSC Chemistry Marathon Archive

Oh, my trials never had the Tony question though.

 

[hayabusaboston]

re: HSC Chemistry Marathon Archive

All I can say is, multiple choice fucked me up, always has. NO BLOODY IDEA WHY.

Well it didnt fuck me up really, I came first by like 10 marks, but I had significantly lower score on MC than I hoped for. Anyone else have this MC problem? ALWAYS getting suspiciously lower than what you thought u would?

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

Oh, my trials never had the Tony question though.

i greatly simplified the question and gave the student a name lol (oh so maybe u didnt get an ethanol-mass calculation question)

 

[Menomaths]

re: HSC Chemistry Marathon Archive

I didn't. I guess my teacher edited it out because it would be too hard for us haha.

 

[Menomaths]

re: HSC Chemistry Marathon Archive

All I can say is, multiple choice fucked me up, always has. NO BLOODY IDEA WHY.

Well it didnt fuck me up really, I came first by like 10 marks, but I had significantly lower score on MC than I hoped for. Anyone else have this MC problem? ALWAYS getting suspiciously lower than what you thought u would?

That usually happens to Physics for me. So many trick questions there...

 

[AnimeX]

re: HSC Chemistry Marathon Archive

@AnimeX - well done on the solution, its correct!

oh dw about the trial, do actual HSC or something, its way better. The trial i did in school had like citric acid titration, arguments for and against for 'carbon neutral' of ethanol, and some other stuff (very low amount of rote learning question). Also the teacher didnt provide solutions (but they did have solutions...), we only went through the paper as a class

So the 1.38g was right? all I didn't do was do exact values?

So does the yeast remain a constant mass and doesn't affect the total mass? so it just stays there?

Yay , haha.

I had same queston. Hold up, did we all do independent trial here?

What'd u all get? I'm a tad unsure whether to say first cos u either all smashed me, or I got around the same as u, or I smashed u. Anythings possible lol.

Oooh, I did this paper aswell hahaha.

All I can say is, multiple choice fucked me up, always has. NO BLOODY IDEA WHY.

Well it didnt fuck me up really, I came first by like 10 marks, but I had significantly lower score on MC than I hoped for. Anyone else have this MC problem? ALWAYS getting suspiciously lower than what you thought u would?

I screwed up MC aswell (11/20).... almost lowest in my class. Did pretty well for the rest of the paper though xD. What did you get in the MC?

 

[someth1ng]

re: HSC Chemistry Marathon Archive

You should really be getting 18+/20, preferably 19+/20 if you want a B6. Honestly, the MC questions test basic understanding.

 

[hayabusaboston]

re: HSC Chemistry Marathon Archive

You should really be getting 18+/20, preferably 19+/20 if you want a B6. Honestly, the MC questions test basic understanding.

I got 19 or 20/20 first go through the 2004-2012 HSC papers, HSC ones are somewhat so much easier than the ones my teacher gives us.

 

[someth1ng]

re: HSC Chemistry Marathon Archive

I got 19 or 20/20 first go through the 2004-2012 HSC papers, HSC ones are somewhat so much easier than the ones my teacher gives us.

I can't really imagine anything that's within the syllabus boundaries where you can't get at least 15+/20.

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

Question: Big bob loves sodium hydrogen carbonate because he used this as his primary standard (in which he used to make a standard solution) to calculate the concentration of hydrochloric and sulfuric acid. Explain why you should not conduct titration with sodium hydrogen carbonate to find the concentration of an unknown acetic acid solution?

 

[Frie]

re: HSC Chemistry Marathon Archive

For the above question: I'm guessing it has something to do with the fact that sodium hydrogen carbonate will act as a weak base in this case, and because acetic acid is also a weak acid, it makes the change in pH really minute. Therefore, hard to find suitable indicator because pH change isn't that great. It could be used with HCl and H2SO4 because it would be weak base + strong acid, hence equivalence point of around 5, and pH change would be from like 2 - 8.

Multiple Choice Question

Sodium hydride (NaH) reacts with water as follows -

NaH (s) + H2O (l) -> Na+ (aq) + OH- (aq) + H2 (g)

This reaction should be classified as:

A: Acid-base but not redox.
B: Redox but not acid-base.
C: Both acid-base and redox.
D: Neither redox nor acid-base.

Extra stuff: If you choose acid-base and/or redox, can you please provide and explanation using equations.

 

[Menomaths]

re: HSC Chemistry Marathon Archive

Sodium Hydrogen Carbonate is a buffer

 

[Frie]

re: HSC Chemistry Marathon Archive

Sodium Hydrogen Carbonate is a buffer

If what you say is true, then how come it can be used for sulfuric and hydrochloric acid, as buffers affect both weak and strong acid/bases.

 

[HeroicPandas]

re: HSC Chemistry Marathon Archive

For the above question: I'm guessing it has something to do with the fact that sodium hydrogen carbonate will act as a weak base in this case, and because acetic acid is also a weak acid, it makes the change in pH really minute. Therefore, hard to find suitable indicator because pH change isn't that great. It could be used with HCl and H2SO4 because it would be weak base + strong acid, hence equivalence point of around 5, and pH change would be from like 2 - 8.


.

great work, exactly what i was looking for!

Sodium Hydrogen Carbonate is a buffer

yes, u can say this aswell