CSSA chem trial (1 Viewer)

[Enigmatic Eve]

Whats the standard conditions question?! Is that the standard potentials or was is about SLC/STP?

 

[Heinz]

Whats the standard conditions question?! Is that the standard potentials or was is about SLC/STP?

Arent they the same thing? The one that asked what where the conditions used for getting the standard reductions used to calculate the EMF, why is it necessary?

 

[Enigmatic Eve]

Oh no!!!! So the conditions used to determine those standard potentials was STP and SLC??! I remember writing crap about keeping the conditions constant (such as temperature, pressure, concentration). Lol... I didnt know the answer to that question, so I made up anything.. worth 3 marks.. I hope they'll give me at least one!! Lol

 

[Heinz]

Oh no!!!! So the conditions used to determine those standard potentials was STP and SLC??! I remember writing crap about keeping the conditions constant (such as temperature, pressure, concentration). Lol... I didnt know the answer to that question, so I made up anything.. worth 3 marks.. I hope they'll give me at least one!! Lol

Thats what I interpreted the question as Hope I read it correctly...

 

[Zarathustra]

Oh crap!!! Can't believe it!!! I got that sulfur/carbon question wrong!! Didn't read the q properly!! How many marks was it worth?!! Dude... I totally forgot about the carbon: eqn I used was S + O2 ----> SO2
Anyway... just agreeing with everyone that the Chemistry Catholic trials were easier than I expected!! Yay!!!
For the molarity question, I got 0.3mol/L. Is that the correct answer?!! I sure hope it is!!!
Lol... I was blown off by the standard potentials questiong.... made a lot of crap up.... hopefully I can scab at least one mark for it.... hee hee!
Anyways, good luck everyone for the rest of your trials!!
Take care

I got 0.3mol/L as well but my working out seemed iffy - to say the least. I wrote that as sulfuric acid is diprotic it would be 2 times as many moles of sodium hydroxide - then multiplied it by the ratio given - 3/2 - so 0.3 mol/L - is this correct?
I couldn't balance the equation - I had about 90 minutes to as well...

 

[Zeppelin]

That test was WAY too easy. I finished it before two hours were up. I'm quite certain I should get over 80%.

 

[Premus]

Hey..

what did u guys get for the titration question?...i got 1M haha
i used pH = -log (H30) and some other crap.... im pretty sure its wrong

Thanks!

 

[keitaro]

can someone tell me what the long response questions were please?!?!?!

 

[sig]

Titration Question:
2NaOH + H2SO4 --> Na2SO4 + 2H2O

NaOH
volume = 0.02L concentration = ?

H2SO4
volume = 0.03L concentration = 0.1 mol/L wasn't it?
n=cv n = 0.003 mole

NaOH = 2n therefore 0.006

C = n/v
C = 0.006 / 0.02 = 0.3mol/L

Sulfur Question
0.1% of Sulfur in 10 million Kg of Coal...

10,000Kg of Sulfur

I just used S + O2 -> SO2

Found moles (m/M) then got something near 7 million litres....

 

[withoutaface]

Thats what I interpreted the question as Hope I read it correctly...

The second part of that question was also ambiguous, what is important? Did it mean the conditions or the standard potential values?

 

[Li0n]

lol yeah damn i knew it would have been 0.3, cause i divided by 2 instead of multiplied lol. I did both in the exam then im like hmm this is a trick question!, all the idiots will pick 0.3 because it looks more real instead of 0.075, but it looks like i was the one that was tricked >.<

withoutaface : i have no idea, thats the CSSA crew for yah, the ambigous kings!

i screwed all the calculation ones now thats approx 10 marks gone...

 

[kofmaster]

yeah here are a couple that i can remember

Haber process impact on society

AAS impact on society and environment

The prac: finding molar heat of combustion of an alkanol - justify your procedure.

the chem of art long answer was on bohr model ...

thats all i can really remember.
hope that helps

really we for our long response, i think our teacher changed it or something cos we had
arrhenius, bronsted - lowry and davy contribution and its impact on society

AAS impact on society and environment

methods of purifying water - (eutrophication)

and for shipwrecks

deep ocean's effect on corrosion of metal

what did you guys get for your long response

 

[coca cola]

yeah i got 0.3 M and so did heaps of people at my school for the titration so fingers crossed. i thought it was a pretty nice paper, they left so much out but i guess its always like that. the chem of art elective was pretty easy. i know ppl at my school didnt like the shipwrecks last question, so how did you guys find that.
for the sulfur/coal question
i got 0.1/100 times 10 000 000
then transfer to g
then do n=m/MM
then using equation
S2 + 202 ---- 2SO2.
so times n times two to get the SO2.
and then i used n=V/Vm
and i ended up with 7 million something.
haha it was so screwed.
hopefully ill get a couple of marks
thought the trial was pretty easy overall. was expecting much much worse!!!

I got 0.3mol/L as well but my working out seemed iffy - to say the least. I wrote that as sulfuric acid is diprotic it would be 2 times as many moles of sodium hydroxide - then multiplied it by the ratio given - 3/2 - so 0.3 mol/L - is this correct?

for the titration the answer is just 0.100 mole, 0.3 is definately wrong, you and your friends proly took the 30ml instead of 10ml for the acid.

so you should lose one mark for it.

and for the volumn its 8 million litres to 1 sig.fig since the least accurate data in the question is to 1 sig.fig.

good luck with the physics and math ccsa trial if anyone of you do it.

 

[coca cola]

30g = 30 ml (since the Q specifies that 1 ml/g)

therefore the total volume in the flask is 30ml, but 20ml is already occupied by the NaOH solution already in there.

therefore there must be only 10ml of H2SO4 added.

volume ratio is 2:1, mole ratio is 1:2. therefore molarity must be equal.

 

[sig]

maybe i'm deluding myself but didn't it say the electron balance was 'zeroed'?

 

[xeriphic]

yer I agree the fact that some of the questions asked wasn't even referred to the syllabus, by the way I wasn't so sure about the question in multiple choice about the pH of H2SO4

also for shipwrecks, what did you guys put as the half equation for the electrolysis

 

[Enigmatic Eve]

for the titration the answer is just 0.100 mole, 0.3 is definately wrong, you and your friends proly took the 30ml instead of 10ml for the acid.

so you should lose one mark for it.

and for the volumn its 8 million litres to 1 sig.fig since the least accurate data in the question is to 1 sig.fig.

good luck with the physics and math ccsa trial if anyone of you do it.

are u serious?! well... i got the titration wrong then... does it matter if we didnt round the volume to 1 significant figure? will we lose a mark for that?!

 

[Enigmatic Eve]

yer I agree the fact that some of the questions asked wasn't even referred to the syllabus, by the way I wasn't so sure about the question in multiple choice about the pH of H2SO4

ooh... was the answer D: 1.9???

 

[xt3rm]

I'm glad they didn't ask anything on those stuppid batteries.

I realised i'd have heaps of tiem left so I started going really slow during the middle and looking around and stuff, and i ended up finishing 5mins before the end. Gave myself a bit of a scare.

I got 0.3M

I didn't get that sulfur question cos ours was modified: it had questions stuck on top of the original questions!!

 

[xeriphic]

hmm I got 1.6

and people in our school got 0.9

since H2SO4 is diprotic, what exactly do you do to find the pH when given concentration