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CSSA 2007 Chemistry Trial Examination thoughts (3 Viewers)

Chinmoku03

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I was thinking the difference between an oxygen radical and an oxygen atom "might" be that one has 3 pairs of electrons whereas the other has 2 pairs and 2 single electrons flying around. Don't trust me on that tho, I couldn't figure out whether what I thought was true or not, so I just guessed no difference in the end >.>;
 

tehsky

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Multiple choice also effed me up =X
i guessed a fair few
and i swear to god, i forgot how to balance the fermentation reaction. awesome huh? =[[ stupid mental blocks!
 

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tehsky said:
Multiple choice also effed me up =X
i guessed a fair few
and i swear to god, i forgot how to balance the fermentation reaction. awesome huh? =[[ stupid mental blocks!
Apparently my last Chemistry teacher said oxidation states were out of the syllabus not too long ago so we didn't learn it.
Then we got a question on oxidation states :(
 

squance

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Hey!! Im from Victoria and was just browsing???

You guys get trial exams??? Does it get marked by the school or the officials??? How many do you get to do???
 

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squance said:
Hey!! Im from Victoria and was just browsing???

You guys get trial exams??? Does it get marked by the school or the officials??? How many do you get to do???
Trial exams are marked by school teachers, that I know of.
The trial exams are a series of exams that simulate our HSC and assess the entire content of the course, and we need one trial exam for each course.
 

Chinmoku03

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tehsky said:
Multiple choice also effed me up =X
i guessed a fair few
and i swear to god, i forgot how to balance the fermentation reaction. awesome huh? =[[ stupid mental blocks!
I dunno why, but I kept thinking that glucose fermented to produce ethanol + water and was sitting there going: "WTF, can't balance" >.<; Luckily, I decided near the end of the exam to go: "Screw it, let's try carbon dioxide instead as a wild guess." Behold, a balanced fermentation equation. I was like: "..." when I saw that ^.^;
 
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for those of you who don't know BOD = biochemical oxygen demand and its a test for h20 quality, you use aerobic organisms to decompose organic material over a 5-day period at 25C, the difference of the DO at the begining and end of 5 days in BOD.
i think the exam was good slightly challenging but pretty easy, finished it with 15 min to spare. i did the biochem option which was SO easy! silly teacher wanted to give me the replacement questions for it!!! (the rest of my class is doing industrial and they havent finished, i finished biochem ages ago!)
hope you all went well :)
 

Jessica14

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wrxsti said:
yer exactly what i did..... got "D" in the end :)
Yay i guessed D by doing "eenie meenie mynie moe" coz i had no idea. Luck was on my side on firday.

:)
 

darksouljah

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lol... anyway.. what was the answer for the oxidation state in the multiple choice?? i guessed that and put A (i think!) where its from 0 -2....
 

wrxsti

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darksouljah said:
lol... anyway.. what was the answer for the oxidation state in the multiple choice?? i guessed that and put A (i think!) where its from 0 -2....
lol sorry .... i am 99% sure its C)
 

yoakim

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2opinion8d said:
I think the BOD question was something along the lines of describing the test for BOD and evaluate its effectiveness for control and monitoring eutrophication...

I'm not sure how many marks i'll get but i basically defined BOD and then described the test:
Using a DO sensor on day zero and then again after placing the sample of water in a brown capped bottle in the dark at 20C for 5 days. The BOD is the difference in the two DO values.

I then talked about how when algal blooms, present because of eutrophication, die, the decomposers use up oxygen in the water to in order to break them down... Thus water that has been plagued by algal blooms has a very high BOD. Therefore BOD can be used as an indicator for algal blooms and eutrophication as the higher the BOD the greater the extent of eutrophication.
I finished off by saying although its useful as a test for monitoring eutrophication it should not be used alone as high BOD's can be due to other factors such as sewage contamination. Therefore further tests to determine nitrogen and phosphate concentration of the water should be carried out.

Briefly, thats how I interpreted the question anyway, any one else get anything similar?

and Halaby's congrats on ur first post :)
That's EXACTLY what I did haha. Those 3 main parts and talking about the 10:1 (N:p) ratio in addition with BOD tests.

For q.14 I also put down D as; since it does state oxygen ATOM rather than molecule, hence it has 2 free electrons and does not differ with the electron 'arrangement' with an oxygen free radical, despite the radical having 1 less free electron.
I put down +4 to +3 for the oxidation state...

From my view it was an alright exam.
 

schmetterling

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omg wow.
im like so overly jealouss of u ppl!
u think it was easy? dammn u must be an uLTRa smarty!
okay i liek didnt even get to answer that concerntration % question.. in fact i cant evn rememba wat it was.
that was so hard.
and i did the forensic Chem option. i totally went mind balnk .
im so sad cos i found it hard. and now its gonna birng my average down:(
good luck!
i iwhs i was like you ppl!
 

yoakim

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schmetterling said:
omg wow.
im like so overly jealouss of u ppl!
u think it was easy? dammn u must be an uLTRa smarty!
okay i liek didnt even get to answer that concerntration % question.. in fact i cant evn rememba wat it was.
that was so hard.
and i did the forensic Chem option. i totally went mind balnk .
im so sad cos i found it hard. and now its gonna birng my average down:(
good luck!
i iwhs i was like you ppl!
it was a hard exam, but i guess im just happy with the fact that i got to write down all i knew. but then again that doesnt necessarily guarantee me a band 5/6 mark. this exam was less stressful for me since my teacher left out the option topic, my class havent even started it yet, so you're waay ahead of us. also, i did ALOT of cramming the nights before, and surprisingly, to my luck, the quesitons such as BOD/eutrophication and the other 'not so common' type questions were the ones that i studied in depth for the nights before. and for the oxidation state question, i guessed the answer, and probably got it wrong, since i forgot how to calculate the oxidation states. dont worry about what others do and how they perform, it makes chemistry seem lifeless.

personally, concentrating on my own task and what i need to get done and what i need to learn, helps me to not to be distracted by other people's crazy band 6 results. chemistry doesnt require ultra smart people, but it does require logic and a passion. :) People have said that the HSC is almost always harder than the trials. Besides, the trials are named the 'trials' for a reason :) so there's no need to despair coz you'll do better in the hsc.
 
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Chinmoku03

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schmetterling said:
omg wow.
im like so overly jealouss of u ppl!
u think it was easy? dammn u must be an uLTRa smarty!
okay i liek didnt even get to answer that concerntration % question.. in fact i cant evn rememba wat it was.
that was so hard.
and i did the forensic Chem option. i totally went mind balnk .
im so sad cos i found it hard. and now its gonna birng my average down:(
good luck!
i iwhs i was like you ppl!
I posted what I reckoned was the right way to solve Q15 a couple of pages ago.

For Q15, I think what you're spose to do is match the wavelength with the element in the bottom table, then find the concentration of that element by using the absorbance level of each element and the graph to find which element had 1.5ppm (I think it was 1.5... x.x; )
^Hope you got the right answer >.<;

it was a hard exam, but i guess im just happy with the fact that i got to write down all i knew. but then again that doesnt necessarily guarantee me a band 5/6 mark. this exam was less stressful for me since my teacher left out the option topic, my class havent even started it yet, so you're waay ahead of us. also, i did ALOT of cramming the nights before, and surprisingly, to my luck, the quesitons such as BOD/eutrophication and the other 'not so common' type questions were the ones that i studied in depth for the nights before. and for the oxidation state question, i guessed the answer, and probably got it wrong, since i forgot how to calculate the oxidation states. dont worry about what others do and how they perform, it makes chemistry seem lifeless.
*Wants to cry really badly at not getting a CFC question for god knows how many times now T.T
 
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beentherdunthat

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chousta said:
hey,

are you guys able to post this exam up?
:wave: Nope. No-one has the exam. The security period is still up.

And btw people... I got my mark back... I got 80 *Depressed*... ah well, thats for only studying the day before... :mad1:

But wth, no time to feel sorry for myself. Trial 2 is coming up...!!! :)
 

beentherdunthat

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Hey people. The answer to the oxygen question is... D!!!
hahahaha.

I got the answer sheet!!! :) Teachers handed out solutions coz they finished marking already. Did anyone get their marks back??
 

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